Simple time tracking functionality added. Time can be logged at issue or project level.

There's no aggregation reports for now, it's just possible to see all time entries for a project or an issue.
A new "activities" enumeration is added.
Permission for a role to log time must be set (new "Time tracking" section in role permissions screen).

git-svn-id: http://redmine.rubyforge.org/svn/trunk@368 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/permission.rb

@@ -30,7 +30,8 @@ class Permission < ActiveRecord::Base
     1100 => :label_news_plural,
     1200 => :label_document_plural,
     1300 => :label_attachment_plural,
-    1400 => :label_repository
+    1400 => :label_repository,
+    1500 => :label_time_tracking
   }.freeze
   
   @@cached_perms_for_public = nil