Do away with InstanceMethods for CoreExtensions::Extensions

middleman-core/lib/middleman-core/core_extensions/extensions.rb

@@ -47,7 +47,6 @@ module Middleman
           app.config[:autoload_sprockets] = (ENV['AUTOLOAD_SPROCKETS'] == 'true') if ENV['AUTOLOAD_SPROCKETS']
 
           app.extend ClassMethods
-          app.send :include, InstanceMethods
           app.delegate :configure, to: :"self.class"
         end
       end
@@ -56,15 +55,13 @@ module Middleman
       module ClassMethods
         # Add a callback to run in a specific environment
         #
-        # @param [String, Symbol] env The environment to run in
+        # @param [String, Symbol] env The environment to run in (:build, :development)
         # @return [void]
         def configure(env, &block)
           send("#{env}_config", &block)
         end
       end
 
-      # Instance methods
-      module InstanceMethods
       # This method is available in the project's `config.rb`.
       # It takes a underscore-separated symbol, finds the appropriate
       # feature module and includes it.
@@ -170,7 +167,7 @@ module Middleman
 
             ::Middleman::Extension.activated_extension(klass)
           end
-          end
+
         end
       end
     end