Fix setting simple values to the new config.x

Previously setting simple values to the config.x object resulted in the
following:

    config.x.super_debugger = true
    config.x.super_debugger #=> {}

Which was against the examples showed in the changelog/release notes.

guides/source/4_2_release_notes.md

@@ -84,7 +84,7 @@ Please refer to the [Changelog][railties] for detailed changes.
     # config/environments/production.rb
     config.x.payment_processing.schedule = :daily
     config.x.payment_processing.retries  = 3
-    config.x.super_debugger = true
+    config.x.super_debugger              = true
     ```
 
     These options are then available through the configuration object:
@@ -93,7 +93,6 @@ Please refer to the [Changelog][railties] for detailed changes.
     Rails.configuration.x.payment_processing.schedule # => :daily
     Rails.configuration.x.payment_processing.retries  # => 3
     Rails.configuration.x.super_debugger              # => true
-    Rails.configuration.x.super_debugger.not_set      # => nil
     ```
 
     ([Commit](https://github.com/rails/rails/commit/611849772dd66c2e4d005dcfe153f7ce79a8a7db))

railties/CHANGELOG.md

@@ -22,14 +22,13 @@
         # config/environments/production.rb
         config.x.payment_processing.schedule = :daily
         config.x.payment_processing.retries  = 3
-        config.x.super_debugger = true
+        config.x.super_debugger              = true
 
     These configuration points are then available through the configuration object:
 
         Rails.configuration.x.payment_processing.schedule # => :daily
         Rails.configuration.x.payment_processing.retries  # => 3
         Rails.configuration.x.super_debugger              # => true
-        Rails.configuration.x.super_debugger.not_set      # => nil
 
     *DHH*
 

railties/lib/rails/application/configuration.rb

@@ -155,15 +155,21 @@ module Rails
       def annotations
         SourceAnnotationExtractor::Annotation
       end
-      
+
       private
-        class Custom
+        class Custom #:nodoc:
           def initialize
             @configurations = Hash.new
           end
-    
+
           def method_missing(method, *args)
-            @configurations[method] ||= ActiveSupport::OrderedOptions.new
+            if method =~ /=$/
+              @configurations[$`.to_sym] = args.first
+            else
+              @configurations.fetch(method) {
+                @configurations[method] = ActiveSupport::OrderedOptions.new
+              }
+            end
           end
         end
     end

railties/test/application/configuration/custom_test.rb

@@ -3,13 +3,20 @@ require 'application/configuration/base_test'
 class ApplicationTests::ConfigurationTests::CustomTest < ApplicationTests::ConfigurationTests::BaseTest
   test 'access custom configuration point' do
     add_to_config <<-RUBY
-      config.x.resque.inline_jobs = :always
-      config.x.resque.timeout     = 60
+      config.x.payment_processing.schedule = :daily
+      config.x.payment_processing.retries  = 3
+      config.x.super_debugger              = true
+      config.x.hyper_debugger              = false
+      config.x.nil_debugger                = nil
     RUBY
     require_environment
 
-    assert_equal :always, Rails.configuration.x.resque.inline_jobs
-    assert_equal 60, Rails.configuration.x.resque.timeout
-    assert_nil Rails.configuration.x.resque.nothing
+    x = Rails.configuration.x
+    assert_equal :daily, x.payment_processing.schedule
+    assert_equal 3, x.payment_processing.retries
+    assert_equal true, x.super_debugger
+    assert_equal false, x.hyper_debugger
+    assert_equal nil, x.nil_debugger
+    assert_nil x.i_do_not_exist.zomg
   end
 end