title: how to add Headers when connect to websocket?
body: <p>we set up websocket topic with Spring websocket, and then the client side is using Stomp.js to subscribe it; 
  it works fine if connect to the websocket service directly; but now we set up Kong as the API Gateway in front of the websocket service; it needs to set header "Host: websocket.com" when connect to it; 
  But it doesn't work with Stomp.js; </p>
  
  <pre><code>var url='http://xx.xx.xx.xx:8000/websocket/tracker';
  var socket = new SockJS(url);
  stompClient = Stomp.over(socket);
  var thisheaders={
          Host:'websocket.com'
  };
  stompClient.connect(thisheaders, function (frame) {
      setConnected(true);
      console.log('Connected: ' + frame);
      stompClient.subscribe('/topic/greetings', function (greeting) {
          showGreeting(JSON.parse(greeting.body).content);
      });
  });
  </code></pre>
  
  <p>Does anyone know how to add the headers for it? Or the Stomp.js just doesn't support to add headers?  </p>