Added support for time zones. Thanks Luke Plant for the review. Fixed #2626.

For more information on this project, see this thread:
http://groups.google.com/group/django-developers/browse_thread/thread/cf0423bbb85b1bbf



git-svn-id: http://code.djangoproject.com/svn/django/trunk@17106 bcc190cf-cafb-0310-a4f2-bffc1f526a37