Fix issue #58: Django 1.1 introduced NullBooleanField which broke stickying.
Fix issue #58: Django 1.1 introduced NullBooleanField which broke stickying.


git-svn-id: 135a05d4c41af105ef1c0134ae9ab473155b4026@42 8fd21cde-4a2f-0410-9917-19c3686e4e0c

farstarinc/django-forum,incuna/django-forum-pinax,dafrito/django-forum,alcides/django-forum