Merged the newforms-admin branch into trunk.

This is a backward incompatible change. The admin contrib app has been
refactored. The newforms module has several improvements including FormSets
and Media definitions.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7967 bcc190cf-cafb-0310-a4f2-bffc1f526a37