Merge pull request #1882 from smartdevicelink/bugfix/issue_1881_transport_broker_npe

Fix NPE in TransportBorker

Author: joeygrover

android/sdl_android/src/main/java/com/smartdevicelink/transport/TransportBroker.java

@@ -764,10 +764,10 @@ public void removeSession(long sessionId) {
      * Method to shut down RouterServiceMessenger
      */
     private void shutDownRouterServiceMessenger() {
-        routerServiceMessenger = null;
         if (routerServiceMessageEmitter != null) {
             routerServiceMessageEmitter.close();
         }
         routerServiceMessageEmitter = null;
+        routerServiceMessenger = null;
     }
 }