Add premessage-deflate extension handler for HTTP WebSocket

Add premessage-deflate extension handler for HTTP WebSocket.

Motivation:
- Need to compress HTTP WebSocket frames payload.

Modifications:
- Remove UTF8 checking of WebSocketFrames from frame decoder in order to
allow compressed frames to go to the next handler.
- Add a WebsocketPremessageDeflateHandler to initialize the frame deflater/inflater if client is compatible with deflate extension.

Result:
First version of the implementation for feedback.
About the maxWindow, I'm facing a limitation of the JdkZlibEncoder that doesn't handle the windowSize at: 
```java
public static ZlibEncoder newZlibEncoder(ZlibWrapper wrapper, int compressionLevel, int windowBits, int memLevel) {
        if (PlatformDependent.javaVersion() < 7) {
            return new JZlibEncoder(wrapper, compressionLevel, windowBits, memLevel);
        } else {
            return new JdkZlibEncoder(wrapper, compressionLevel);
        }
}
```
So, for the moment, I cannot manage server_max_window_bits and client_max_window_bits  properly.