Per project forums added.

Permissions for forums management can be set in "Admin -> Roles & Permissions".
Forums can be created on the project settings screen ("Forums" tab).
Once a project has a forum, a "Forums" link appears in the project menu.
For now, posting messages in forums requires to be logged in. Files can be attached to messages.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@529 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/permission.rb

@@ -31,7 +31,8 @@ class Permission < ActiveRecord::Base
     1200 => :label_document_plural,
     1300 => :label_attachment_plural,
     1400 => :label_repository,
-    1500 => :label_time_tracking
+    1500 => :label_time_tracking,
+    2000 => :label_board_plural
   }.freeze
   
   @@cached_perms_for_public = nil