Add WebSocket Extension handlers for client and server.
Add permessage-deflate and deflate-frame WebSocket extension
implementations.

Motivation:

Need to compress HTTP WebSocket frames payload.

Modifications:

- Move UTF8 checking of WebSocketFrames from frame decoder to and
external handler.
- Change ZlibCodecFactory in order to use ZLib implentation instead of
JDK if windowSize or memLevel is different from the default one.
- Add WebSocketServerExtensionHandler and
WebSocketClientExtensionHandler to handle WebSocket Extension headers.
- Add DeflateFrame and PermessageDeflate extension implementations.