Keep track of who deletes forum post/topic/comment

Previously it would look like the creator of it was the one who
deleted/undeleted it, even if it was someone else.

app/models/comment.rb

@@ -173,7 +173,7 @@ class Comment < ActiveRecord::Base
   end
 
   def delete!
-    update_attribute(:is_deleted, true)
+    update_attributes(:is_deleted => true)
   end
 end