Fixed #5610 -- Added the ability for dumpdata to take individual model names,...

Fixed #5610 -- Added the ability for dumpdata to take individual model names, as well as entire applications. Thanks to David Reynolds for his work on this patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9921 bcc190cf-cafb-0310-a4f2-bffc1f526a37