Fixed #7254 -- Added an '--exclude' option to dumpdata, allowing specific...

Fixed #7254 -- Added an '--exclude' option to dumpdata, allowing specific applications to be removed from the dump output. Thanks to Carl Karsten for the idea and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7615 bcc190cf-cafb-0310-a4f2-bffc1f526a37