Fix bugs in WebSocket writeMessage

Signed-off-by: Julien Viet <julien@julienviet.com>
Update comment to reference the Netty websocket close frame bug for version 0

Signed-off-by: Julien Viet <julien@julienviet.com>
Merge pull request #897 from vietj/websocket-write-bug

Fix bugs in WebSocket writeMessage