Fixed #4617 -- Added `raise_exception` option to `permission_required`...

Fixed #4617 -- Added `raise_exception` option to `permission_required` decorator to be able to raise a PermissionDenied exception instead of redirecting to the login page.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16607 bcc190cf-cafb-0310-a4f2-bffc1f526a37