Add .disconnect clean up OnDestroy
Add .disconnect clean up OnDestroy

sjmf/ng2-stompjs-demo,JimiC/ng2-stompjs-demo,stomp-js/ng2-stompjs-demo,sjmf/ng2-stompjs-demo,stomp-js/ng2-stompjs-demo,JimiC/ng2-stompjs-demo,JimiC/ng2-stompjs-demo,sjmf/ng2-stompjs-demo,stomp-js/ng2-stompjs-demo