Fixed #17286 -- Made sure all cache backends are set up to connect to the...

Fixed #17286 -- Made sure all cache backends are set up to connect to the signal handler that closes the cache connection when the request has been processed. Thanks, gnosek.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17479 bcc190cf-cafb-0310-a4f2-bffc1f526a37