Fixed #13308 -- Ensured that dumpdata correctly interacts with router...

Fixed #13308 -- Ensured that dumpdata correctly interacts with router allow_syncdb directions. Thanks to Francis (wizard_2) for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12940 bcc190cf-cafb-0310-a4f2-bffc1f526a37