Fixed #12534 -- Loosened the the security check for "next" redirects after...

Fixed #12534 -- Loosened the the security check for "next" redirects after logins slightly to allow paths that contain spaces. Thanks for the patch, jnns and aaugustin.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15702 bcc190cf-cafb-0310-a4f2-bffc1f526a37