upgrade to  websocket not happening
I'm trying to establish a websocket connection with the push Notification server from the examples

`var conn = new WebSocket('ws://10.0.0.23:8080');`

but the connection is not upgraded to websocket.

request header:
```
GET ws://10.0.0.23:8080/ HTTP/1.1
Host: 10.0.0.23:8080
Connection: Upgrade
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket
Origin: http://xxx
Sec-WebSocket-Version: 13
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Safari/537.36
Accept-Encoding: gzip, deflate
Accept-Language: de,en-US;q=0.9,en;q=0.8
Sec-WebSocket-Key: CbYPFT8CVPy18w6mtYGQNw==
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits
```

response header
```
Connection:Upgrade
Sec-WebSocket-Protocol:0
Sec-WebSocket-Version:13
Upgrade:websocket
X-Powered-By:Ratchet/0.4.1
```