[Rails 4.1] Record Identifier: ActionController -> ActionView

There is an `include` in *mock_rails.rb* that seems to be not compatible with Rails 4.1+.  RecordIdentifier (`dom_class`) has moved from ActionController to ActionView.  Ref: http://api.rubyonrails.org/classes/ActionView/RecordIdentifier.html.  You'll have to decide if you want to to do a Rails 4.1 branch or something else.