Adds watch/unwatch functionality at forum topic level (#1912).

Users who create/reply a topic are automatically added as watchers but are now able to unwatch the topic.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1878 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/messages_controller.rb

@@ -24,7 +24,7 @@ class MessagesController < ApplicationController
   verify :method => :post, :only => [ :reply, :destroy ], :redirect_to => { :action => :show }
   verify :xhr => true, :only => :quote
 
-  
+  helper :watchers
   helper :attachments
   include AttachmentsHelper