Merge pull request #7776 from smartinez87/changelog_entry

Add #update_columns entry to AR Changelog. [ci skip]

activerecord/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Added `#update_columns` method which updates the attributes from
+    the passed-in hash without calling save, hence skipping validations and
+    callbacks. `ActiveRecordError` will be raised when called on new objects
+    or when at least one of the attributes is marked as read only.
+
+        post.attributes # => {"id"=>2, "title"=>"My title", "body"=>"My content", "author"=>"Peter"}
+        post.update_columns({title: 'New title', author: 'Sebastian'}) # => true
+        post.attributes # => {"id"=>2, "title"=>"New title", "body"=>"My content", "author"=>"Sebastian"}
+
+    *Sebastian Martinez*
+
 *   Allow before and after validations to take an array of lifecycle events
 
     *John Foley*