diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 00000000..5d126348
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,13 @@
+# editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.rubocop.yml b/.rubocop.yml
index 652f08fb..337be055 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -25,8 +25,6 @@ ClassLength:
   Enabled: false
 Documentation:
   Enabled: false
-Encoding:
-  Enabled: false
 HashSyntax:
   EnforcedStyle: ruby19
 SpaceAroundEqualsInParameterDefault:
diff --git a/middleman-cli/lib/middleman-cli/templates/extension/Rakefile b/middleman-cli/lib/middleman-cli/templates/extension/Rakefile
index 529dfacf..4c62996f 100644
--- a/middleman-cli/lib/middleman-cli/templates/extension/Rakefile
+++ b/middleman-cli/lib/middleman-cli/templates/extension/Rakefile
@@ -4,7 +4,7 @@ Bundler::GemHelper.install_tasks
 require 'cucumber/rake/task'
 
 Cucumber::Rake::Task.new(:cucumber, 'Run features that should pass') do |t|
-  t.cucumber_opts = "--color --tags ~@wip --strict"
+  t.cucumber_opts = '--color --tags ~@wip --strict'
 end
 
 require 'rake/clean'
diff --git a/middleman-core/.rspec b/middleman-core/.rspec
new file mode 100644
index 00000000..5052887a
--- /dev/null
+++ b/middleman-core/.rspec
@@ -0,0 +1 @@
+--color
\ No newline at end of file
diff --git a/middleman-core/cucumber.yml b/middleman-core/cucumber.yml
new file mode 100644
index 00000000..922a378c
--- /dev/null
+++ b/middleman-core/cucumber.yml
@@ -0,0 +1,2 @@
+default: --require features --tags ~@wip
+wip: --require features --tags @wip
\ No newline at end of file
diff --git a/middleman-core/features/chained_templates.feature b/middleman-core/features/chained_templates.feature
index 4647e7eb..27135bf6 100644
--- a/middleman-core/features/chained_templates.feature
+++ b/middleman-core/features/chained_templates.feature
@@ -7,19 +7,19 @@ Feature: Templates should be chainable
     Then I should see "Title</h1>"
     And I should see "Subtitle</h2>"
     And I should see "Sup</h3>"
-    
+
   Scenario: Build chained template
     Given a successfully built app at "chained-app"
     When I cd to "build"
     Then the following files should exist:
       | index.html                                    |
-      | test.html.combobreaker                        |
+      | test.erb.combobreaker                         |
     And the file "index.html" should contain "Title</h1>"
     And the file "index.html" should contain "Subtitle</h2>"
     And the file "index.html" should contain "Sup</h3>"
-    And the file "test.html.combobreaker.html" should contain "Title</h1>"
-    And the file "test.html.combobreaker.html" should contain "Subtitle</h2>"
-    And the file "test.html.combobreaker.html" should contain "Sup</h3>"
+    And the file "test.erb.combobreaker" should contain "Title</h1>"
+    And the file "test.erb.combobreaker" should contain "Subtitle</h2>"
+    And the file "test.erb.combobreaker" should contain "Sup</h3>"
 
   Scenario: Partials are parsed by multiple template engines: Outer template has .erb and inner .md.erb
     Given a fixture app "partial-chained_templates-app"
@@ -32,7 +32,7 @@ Feature: Templates should be chainable
     And a template named "my_partial.html.md.erb" with:
     """
     ## My Partial
-    
+
     <%= 'hello world' %>
     """
     And the Server is running
@@ -61,7 +61,7 @@ Feature: Templates should be chainable
     And a template named "my_partial.html.md.erb" with:
     """
     ## My Partial
-    
+
     <%= 'hello world' %>
     """
     And the Server is running
@@ -90,7 +90,7 @@ Feature: Templates should be chainable
     And a template named "my_partial.html.erb" with:
     """
     <h2>My Partial</h2>
-    
+
     <%= 'hello world' %>
     """
     And the Server is running
diff --git a/middleman-core/fixtures/chained-app/source/test.html.combobreaker.str.erb b/middleman-core/fixtures/chained-app/source/test.erb.combobreaker.str.erb
similarity index 100%
rename from middleman-core/fixtures/chained-app/source/test.html.combobreaker.str.erb
rename to middleman-core/fixtures/chained-app/source/test.erb.combobreaker.str.erb
diff --git a/middleman-core/lib/middleman-core/application.rb b/middleman-core/lib/middleman-core/application.rb
index 9ee3f4b9..6c39af54 100644
--- a/middleman-core/lib/middleman-core/application.rb
+++ b/middleman-core/lib/middleman-core/application.rb
@@ -1,5 +1,3 @@
-# Use ActiveSupport JSON
-require 'active_support/json'
 require 'active_support/core_ext/integer/inflections'
 
 require 'middleman-core/contracts'
diff --git a/middleman-core/lib/middleman-core/core_extensions/default_helpers.rb b/middleman-core/lib/middleman-core/core_extensions/default_helpers.rb
index 71666bab..ba508c4d 100644
--- a/middleman-core/lib/middleman-core/core_extensions/default_helpers.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/default_helpers.rb
@@ -7,7 +7,8 @@ require 'padrino-helpers'
 class Padrino::Helpers::OutputHelpers::ErbHandler
   # Force Erb capture not to use safebuffer
   def capture_from_template(*args, &block)
-    self.output_buffer, buf_was = '', output_buffer
+    self.output_buffer = ''
+    buf_was = output_buffer
     raw = block.call(*args)
     captured = template.instance_variable_get(:@_out_buf)
     self.output_buffer = buf_was
diff --git a/middleman-core/lib/middleman-core/extensions/asset_hash.rb b/middleman-core/lib/middleman-core/extensions/asset_hash.rb
index e3248bd5..bb1389e9 100644
--- a/middleman-core/lib/middleman-core/extensions/asset_hash.rb
+++ b/middleman-core/lib/middleman-core/extensions/asset_hash.rb
@@ -17,7 +17,7 @@ class Middleman::Extensions::AssetHash < ::Middleman::Extension
   def after_configuration
     # Allow specifying regexes to ignore, plus always ignore apple touch icons
     @ignore = Array(options.ignore) + [/^apple-touch-icon/]
-    
+
     app.use ::Middleman::Middleware::InlineURLRewriter,
             id: :asset_hash,
             url_extensions: options.exts,
diff --git a/middleman-core/lib/middleman-core/preview_server.rb b/middleman-core/lib/middleman-core/preview_server.rb
index 4d727bd1..d9f5c172 100644
--- a/middleman-core/lib/middleman-core/preview_server.rb
+++ b/middleman-core/lib/middleman-core/preview_server.rb
@@ -125,8 +125,8 @@ module Middleman
 
             # config.rb
             watcher = files.watch :reload,
-                        path: root,
-                        only: match_against
+                                  path: root,
+                                  only: match_against
 
             # Hack around node_modules in root.
             watcher.listener.ignore(/^node_modules/)
diff --git a/middleman-core/lib/middleman-core/rack.rb b/middleman-core/lib/middleman-core/rack.rb
index a6743c59..3e2a6f25 100644
--- a/middleman-core/lib/middleman-core/rack.rb
+++ b/middleman-core/lib/middleman-core/rack.rb
@@ -102,7 +102,7 @@ module Middleman
 
       begin
         # Write out the contents of the page
-        res.write resource.render({}, { rack: { request: req } })
+        res.write resource.render({}, rack: { request: req })
 
         # Valid content is a 200 status
         res.status = 200
diff --git a/middleman-core/lib/middleman-core/renderers/haml.rb b/middleman-core/lib/middleman-core/renderers/haml.rb
index 7e2b6fbb..24cdced4 100644
--- a/middleman-core/lib/middleman-core/renderers/haml.rb
+++ b/middleman-core/lib/middleman-core/renderers/haml.rb
@@ -40,7 +40,6 @@ module Middleman
 
     # Haml Renderer
     class Haml < ::Middleman::Extension
-
       def initialize(app, options={}, &block)
         super
 
@@ -53,7 +52,7 @@ module Middleman
               modified_options = options.dup
               modified_options[:context] = compiler_options[:context]
 
-              text = template_class.new(nil, 1, modified_options) {text}.render
+              text = template_class.new(nil, 1, modified_options) { text }.render
               super(text, compiler_options)
             end
           end
diff --git a/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb b/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb
index 0285726f..110d9890 100644
--- a/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb
+++ b/middleman-core/lib/middleman-core/sitemap/extensions/proxies.rb
@@ -86,8 +86,8 @@ module Middleman
     end
 
     class Resource
-      def proxy_to(path)
-        throw "Resource#proxy_to has been removed. Use ProxyResource class instead."
+      def proxy_to(_path)
+        throw 'Resource#proxy_to has been removed. Use ProxyResource class instead.'
       end
     end
 
diff --git a/middleman-core/lib/middleman-core/sitemap/resource.rb b/middleman-core/lib/middleman-core/sitemap/resource.rb
index 14b43fd7..4a247cb8 100644
--- a/middleman-core/lib/middleman-core/sitemap/resource.rb
+++ b/middleman-core/lib/middleman-core/sitemap/resource.rb
@@ -48,9 +48,7 @@ module Middleman
         @app         = @store.app
         @path        = path
 
-        if source && source.is_a?(String)
-          source = Pathname(source)
-        end
+        source = Pathname(source) if source && source.is_a?(String)
 
         if source && source.is_a?(Pathname)
           @file_descriptor = ::Middleman::SourceFile.new(source.relative_path_from(@app.source_dir), source, @app.source_dir, Set.new([:source]))
diff --git a/middleman-core/lib/middleman-core/sitemap/store.rb b/middleman-core/lib/middleman-core/sitemap/store.rb
index f7af3bd2..54e6b1ce 100644
--- a/middleman-core/lib/middleman-core/sitemap/store.rb
+++ b/middleman-core/lib/middleman-core/sitemap/store.rb
@@ -187,23 +187,24 @@ module Middleman
 
           @app.logger.debug '== Rebuilding resource list'
 
-          @resources = @resource_list_manipulators.reduce([]) do |result, m|
+          @resources = []
+
+          @resource_list_manipulators.each do |m|
             @app.logger.debug "== Running manipulator: #{m[:name]}"
-            newres = m[:manipulator].send(m[:custom_name] || :manipulate_resource_list, result)
+            @resources = m[:manipulator].send(m[:custom_name] || :manipulate_resource_list, @resources)
 
             # Reset lookup cache
             reset_lookup_cache!
 
             # Rebuild cache
-            newres.each do |resource|
+            @resources.each do |resource|
               @_lookup_by_path[resource.path] = resource
               @_lookup_by_destination_path[resource.destination_path] = resource
             end
 
-            newres
+            invalidate_resources_not_ignored_cache!
           end
 
-          invalidate_resources_not_ignored_cache!
           @update_count += 1
         end
       end
@@ -223,7 +224,7 @@ module Middleman
       Contract String => String
       def remove_templating_extensions(path)
         # Strip templating extensions as long as Tilt knows them
-        path = path.sub(File.extname(path), '') while ::Tilt[path]
+        path = path.sub(/#{::Regexp.escape(File.extname(path))}$/, '') while ::Tilt[path]
         path
       end
 
diff --git a/middleman-core/lib/middleman-core/sources/source_watcher.rb b/middleman-core/lib/middleman-core/sources/source_watcher.rb
index 82dc8f74..38ac639a 100644
--- a/middleman-core/lib/middleman-core/sources/source_watcher.rb
+++ b/middleman-core/lib/middleman-core/sources/source_watcher.rb
@@ -8,16 +8,14 @@ require 'backports/2.0.0/enumerable/lazy'
 module Listen
   class Silencer
     # TODO: switch type and path places - and verify
-    def silenced?(relative_path, type)
+    def silenced?(relative_path, _type)
       path = relative_path.to_s
 
       # if only_patterns && type == :file
       #   return true unless only_patterns.any? { |pattern| path =~ pattern }
       # end
 
-      if only_patterns
-        return !only_patterns.any? { |pattern| path =~ pattern }
-      end
+      return !only_patterns.any? { |pattern| path =~ pattern } if only_patterns
 
       ignore_patterns.any? { |pattern| path =~ pattern }
     end
diff --git a/middleman-core/lib/middleman-core/template_context.rb b/middleman-core/lib/middleman-core/template_context.rb
index 48498d85..6771ddbe 100644
--- a/middleman-core/lib/middleman-core/template_context.rb
+++ b/middleman-core/lib/middleman-core/template_context.rb
@@ -71,7 +71,8 @@ module Middleman
       engine = extension[1..-1].to_sym
 
       # Store last engine for later (could be inside nested renders)
-      self.current_engine, engine_was = engine, current_engine
+      self.current_engine = engine
+      engine_was = current_engine
 
       # By default, no content is captured
       content = ''
diff --git a/middleman-core/lib/middleman-core/util/data.rb b/middleman-core/lib/middleman-core/util/data.rb
index a02d64e2..781ed5c0 100644
--- a/middleman-core/lib/middleman-core/util/data.rb
+++ b/middleman-core/lib/middleman-core/util/data.rb
@@ -11,11 +11,11 @@ require 'middleman-core/util'
 require 'yaml'
 
 # Parsing JSON data
-require 'active_support/json'
+require 'json'
 
 module Middleman
   module Util
-    module Data      
+    module Data
       include Contracts
 
       module_function
@@ -121,7 +121,7 @@ module Middleman
       Contract String, Pathname => Maybe[[Hash, String]]
       def parse_json(content, full_path)
         begin
-          data = map_value(::ActiveSupport::JSON.decode(content))
+          data = map_value(::JSON.parse(content))
         rescue => e
           $stderr.puts "JSON Exception parsing #{full_path}: #{e.message}"
           return nil