Fixed #10243, #11043 -- Corrected handling of formsets over a ForeignKey that uses to_field, and by extension, fixed the admin for handling fields of that type. Thanks to apollo13 for the initial patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10756 bcc190cf-cafb-0310-a4f2-bffc1f526a37