onOpen() callback function in jquery.atmospehere.js does not fire properly when using long-polling

[freedom1989]

when use long-polling as the transport, onOpen callback function fires not properly.

var socket = $.atmosphere;
request.onOpen(response){
    //here will get "subSocket is undefined".
    subSocket.push(something);
}
var subSocket = socket.subscribe(request);

more details please ref to here:
https://groups.google.com/forum/?fromgroups=#!topic/atmosphere-framework/laiDwX2jIIM
and I think onOpen function should be fired after the subscribe() function finished as the same as we use websocket.
please fix it.

[jfarcand]

Fixed by #833