Expose methods added to Enumerable in the documentation, such as group_by. Closes #6170.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5334 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

 *SVN*
 
+* Expose methods added to Enumerable in the documentation, such as group_by. Closes #6170. [sergeykojin@gmail.com, Marcel Molina Jr.]
+
 * Ensure Chars#tidy_bytes only tidies broken bytes. Closes #6397 [Manfred Stienstra]
 
 * Add 'unloadable', a method used to mark any constant as requiring an unload after each request. [Nicholas Seckar]

activesupport/lib/active_support/core_ext/enumerable.rb

-module Enumerable #:nodoc:
+module Enumerable
   # Collect an enumerable into sets, grouped by the result of a block. Useful,
   # for example, for grouping records by date.
   #
@@ -19,7 +19,7 @@ def group_by
       (groups[yield(element)] ||= []) << element
       groups
     end
-  end 
+  end if RUBY_VERSION < '1.9'
 
   # Calculates a sum from the elements. Examples:
   #