Keep notifier core API consistent

Issue 1:
Remove STOMP unsubscribe test after callback was removed in src

Issue 2:
Updated the vertxbus.js since the current version is old and the server disconnects the clients after some seconds. The new vertxbus.js contains some ping request to prevent the server from closing the connection.

Issue 3:
Updated the activemq download URL. The current https://www.poolsaboveground.com/ mirror returns 403.

Issue 4:
Updated .gitignore to ignore activemq files