This reverts commit b109ff8062 and complement test cases. The change was too hasty, as some form values cannot be json-serialized as is.
b109ff8062
git-svn-id: http://code.djangoproject.com/svn/django/trunk@16616 bcc190cf-cafb-0310-a4f2-bffc1f526a37
git-svn-id: http://code.djangoproject.com/svn/django/trunk@16307 bcc190cf-cafb-0310-a4f2-bffc1f526a37