BinaryEchoTest over LongPolling.

Hi Jeanfrancois 

this is an echo test, with one binary echo message being sent in and expected to be echoed.

Currently it fails and illustrates nicely the "connection establishment" in ```socket.connect()``` going crazy, once the ```.header("Content-Type", "application/octet-stream")``` is set on the ```RequestBuilder```.

I can't get it to work. 

I think that similar stuff used to work in the past, when there was only one GET in establishing the connection and no stuff being sent back for LONG-POLLING in connection establishment.

Thanks for investigating.