STOMP 1.1 Over WebSocket

* update stomp.js library to support STOMP 1.1 (including
  heart-beating).
* The js file was taken from  https://raw.github.com/jmesnil/stomp-websocket/master/dist/stomp.js.
STOMP 1.1 Over WebSocket

* udpate echo.html to use Stomp.over(ws) to pass the SockJS object
Fix second example
Turn off heartbeats in examples - they're unsupported in SockJS
Merge bug25333