Fixed #14025 -- Modified flush to adhere to router sync instructions when...

Fixed #14025 -- Modified flush to adhere to router sync instructions when emmiting post-sync signals. Thanks to linovia for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13466 bcc190cf-cafb-0310-a4f2-bffc1f526a37