Allow binary as a 'protocol'

[mcclymont]

noVNC has removed support for base64 encoding in the latest release: https://github.com/novnc/noVNC/commit/38781d931ec18304f51ed3469faff8387e3cbc55

This means that noVNC ends up sending the header "Sec-WebSocket-Protocol:binary", and vncAuthProxy/txWS can't deal with that because binary is not in the encoders/decoders dicts and txWS returns false from validateHeaders.

[zgoda]

Any chance to merge this?

[jarrodchesney]

The diff looks simple enough to me.

[mcclymont]

@MostAwesomeDude pretty please :)