diff --git a/middleman-core/lib/middleman-core/application.rb b/middleman-core/lib/middleman-core/application.rb
index f8cb7563..0712eed1 100644
--- a/middleman-core/lib/middleman-core/application.rb
+++ b/middleman-core/lib/middleman-core/application.rb
@@ -334,8 +334,9 @@ module Middleman
     end
 
     # Whether we're in a specific environment
+    # @param [Symbol] key
     # @return [Boolean]
-    Contract Bool
+    Contract Symbol => Bool
     def environment?(key)
       config[:environment] == key
     end
diff --git a/middleman-core/lib/middleman-core/core_extensions/front_matter.rb b/middleman-core/lib/middleman-core/core_extensions/front_matter.rb
index d685e994..a133d0ef 100644
--- a/middleman-core/lib/middleman-core/core_extensions/front_matter.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/front_matter.rb
@@ -12,7 +12,7 @@ require 'middleman-core/util/data'
 module Middleman::CoreExtensions
   class FrontMatter < ::Middleman::Extension
     # Try to run after routing but before directory_indexes
-    self.resource_list_manipulator_priority = 10
+    self.resource_list_manipulator_priority = 20
 
     def initialize(app, options_hash={}, &block)
       super
diff --git a/middleman-core/lib/middleman-core/core_extensions/routing.rb b/middleman-core/lib/middleman-core/core_extensions/routing.rb
index 0601d2d0..3e66f3dc 100644
--- a/middleman-core/lib/middleman-core/core_extensions/routing.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/routing.rb
@@ -4,7 +4,7 @@ module Middleman
     class Routing < Extension
       # This should always run late, but not as late as :directory_indexes,
       # so it can add metadata to any pages generated by other extensions
-      self.resource_list_manipulator_priority = 80
+      self.resource_list_manipulator_priority = 10
 
       # Expose the `page` method to config.
       expose_to_config :page
diff --git a/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb b/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb
index aa184df9..b88721de 100644
--- a/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb
+++ b/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb
@@ -23,7 +23,8 @@ class Middleman::Extensions::AutomaticImageSizes < ::Middleman::Extension
 
         if file && file[:full_path].exist?
           begin
-            width, height = ::FastImage.size(file[:full_path].to_s, raise_on_failure: true)
+            full_path = file[:full_path].to_s
+            width, height = ::FastImage.size(full_path, raise_on_failure: true)
             # Check for @2x and @3x image
             retina = full_path.match(/@(\d)x\.[a-zA-Z]{3,4}$/)
             if retina
diff --git a/middleman-core/lib/middleman-core/extensions/minify_javascript.rb b/middleman-core/lib/middleman-core/extensions/minify_javascript.rb
index 4ab0979a..73a75cd0 100644
--- a/middleman-core/lib/middleman-core/extensions/minify_javascript.rb
+++ b/middleman-core/lib/middleman-core/extensions/minify_javascript.rb
@@ -13,7 +13,7 @@ class Middleman::Extensions::MinifyJavascript < ::Middleman::Extension
 
   def ready
     # Setup Rack middleware to minify JS
-    app.use Rack, compressor: chosen_compressor,
+    app.use Rack, compressor: options[:compressor],
                   ignore: Array(options[:ignore]) + [/\.min\./],
                   inline: options[:inline],
                   content_types: options[:content_types],
diff --git a/middleman-core/lib/middleman-core/rack.rb b/middleman-core/lib/middleman-core/rack.rb
index 3e2a6f25..4578005b 100644
--- a/middleman-core/lib/middleman-core/rack.rb
+++ b/middleman-core/lib/middleman-core/rack.rb
@@ -14,6 +14,12 @@ require 'middleman-core/template_renderer'
 ::Rack::Mime::MIME_TYPES['.html'] = 'text/html; charset=utf-8'
 ::Rack::Mime::MIME_TYPES['.htm'] = 'text/html; charset=utf-8'
 
+# Sourcemap format
+::Rack::Mime::MIME_TYPES['.map'] = 'application/json; charset=utf-8'
+
+# Create a MIME type for PHP files (for detection by extensions)
+::Rack::Mime::MIME_TYPES['.php'] = 'text/php'
+
 module Middleman
   class Rack
     extend Forwardable
diff --git a/middleman-core/lib/middleman-core/step_definitions/middleman_steps.rb b/middleman-core/lib/middleman-core/step_definitions/middleman_steps.rb
index 395ff3de..ff256a94 100644
--- a/middleman-core/lib/middleman-core/step_definitions/middleman_steps.rb
+++ b/middleman-core/lib/middleman-core/step_definitions/middleman_steps.rb
@@ -1,15 +1,15 @@
 Then /^the file "([^\"]*)" has the contents$/ do |path, contents|
   write_file(path, contents)
 
-  cd(".") do
+  # cd(".") do
     @server_inst.files.find_new_files!
-  end
+  # end
 end
 
 Then /^the file "([^\"]*)" is removed$/ do |path|
   step %Q{I remove the file "#{path}"}
 
-  cd(".") do
+  # cd(".") do
     @server_inst.files.find_new_files!
-  end
+  # end
 end
diff --git a/middleman-core/lib/middleman-core/step_definitions/server_steps.rb b/middleman-core/lib/middleman-core/step_definitions/server_steps.rb
index 448af3cf..1a80a118 100644
--- a/middleman-core/lib/middleman-core/step_definitions/server_steps.rb
+++ b/middleman-core/lib/middleman-core/step_definitions/server_steps.rb
@@ -1,3 +1,4 @@
+require 'middleman-core/rack'
 require 'rspec/expectations'
 require 'capybara/cucumber'
 
@@ -41,7 +42,7 @@ Given /^the Server is running$/ do
 
   initialize_commands = @initialize_commands || []
 
-  cd(".") do
+  # cd(".") do
     @server_inst = ::Middleman::Application.new do
       config[:watcher_disable] = true
       config[:show_exceptions] = false
@@ -51,9 +52,8 @@ Given /^the Server is running$/ do
       end
     end
 
-    rack = ::Middleman::Rack.new(@server_inst)
-    Capybara.app = rack.to_app
-  end
+    Capybara.app = ::Middleman::Rack.new(@server_inst).to_app
+  # end
 end
 
 Given /^the Server is running at "([^\"]*)"$/ do |app_path|
@@ -66,73 +66,73 @@ Given /^a template named "([^\"]*)" with:$/ do |name, string|
 end
 
 When /^I go to "([^\"]*)"$/ do |url|
-  cd(".") do
+  # cd(".") do
     visit(URI.encode(url).to_s)
-  end
+  # end
 end
 
 Then /^going to "([^\"]*)" should not raise an exception$/ do |url|
-  cd(".") do
+  # cd(".") do
     expect{ visit(URI.encode(url).to_s) }.to_not raise_exception
-  end
+  # end
 end
 
 Then /^the content type should be "([^\"]*)"$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.response_headers['Content-Type']).to start_with expected
-  end
+  # end
 end
 
 Then /^I should see "([^\"]*)"$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).to include expected
-  end
+  # end
 end
 
 Then /^I should see '([^\']*)'$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).to include expected
-  end
+  # end
 end
 
 Then /^I should see:$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).to include expected
-  end
+  # end
 end
 
 Then /^I should not see "([^\"]*)"$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).not_to include expected
-  end
+  # end
 end
 
 Then /^I should see content matching %r{(.*)}$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).to match(expected)
-  end
+  # end
 end
 
 Then /^I should not see content matching %r{(.*)}$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).to_not match(expected)
-  end
+  # end
 end
 
 Then /^I should not see:$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.body).not_to include expected
-  end
+  # end
 end
 
 Then /^the status code should be "([^\"]*)"$/ do |expected|
-  cd(".") do
+  # cd(".") do
     expect(page.status_code).to eq expected.to_i
-  end
+  # end
 end
 
 Then /^I should see "([^\"]*)" lines$/ do |lines|
-  cd(".") do
+  # cd(".") do
     expect(page.body.chomp.split($/).length).to eq lines.to_i
-  end
+  # end
 end