Added the 401 error page to the guest allowed ACL.

Added the 401 error page to guest allowed in ACL.
Added a session->destroy to SecurityPlugin error exit path to force reload of ACL, and generally clean up if there is a authorization error.  Without the 401 page added to the ACL the $dispatcher->forward was getting an unauthorized page and the dispatcher was going into a loop that returned nothing when Phalcon forces the dispatcher to exit