Callback for 'reply-to' messages in temp-queue

Added the ability to define a callback for "reply-to" messages. Example:
var url = 'http://127.0.0.1:15674/stomp';
var ws = new SockJS(url);
var client = Stomp.over(ws);

var on_reply = function(m) {
   alert(m.body);
};

client.connect('guest', 'guest');
client.send('/queue/test', {'reply-to': '/temp-queue/test_temp'}, 'test', on_reply);