Fixed #4667 -- Added support for inline generic relations in the admin. Thanks...

Fixed #4667 -- Added support for inline generic relations in the admin. Thanks to Honza Král and Alex Gaynor for their work on this ticket.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8279 bcc190cf-cafb-0310-a4f2-bffc1f526a37