Added the ability to customize the prefix value on an inline formset. Fixes...

Added the ability to customize the prefix value on an inline formset. Fixes #7899. AThanks for the tip Peter of the Norse.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8060 bcc190cf-cafb-0310-a4f2-bffc1f526a37