ByteBuf is too unqualified for WebSocket messages

[rstoyanchev]

For WebSocket the NettyInbound.receive() which provides ByteBuf's is too unqualified to be useful because there is no way of knowing the boundaries of a complete WebSocket message nor whether it is binary, text, or pong. It's possible to use NettyInbound.receiveObject().cast(WebSocketFrame.class) but it would be nicer if a handler is given something a little less generic and more tailored to a WebSocket interaction -- e.g. a receive method that provides WebSocketFrame's.

A similar improvement on the outbound side would remove the need to specify text vs binary when calling one of the HttpOutbound#upgradeToWebSocketXxx methods since the input would already be WebSocketFrame's.

[smaldini]

Fixed with WebsocketInbound#receiveFrames()