soup: introspection fixes
websocket: server: ignore extensions

With applications running in Chrome, connections will systematically
fail because Chrome will ask for extensions by default
(permessage-deflate; client_max_window_bits) without any doing from a
web application.

The spec [1] says :
"WebSocket clients MAY request extensions to this specification, and
 WebSocket servers MAY accept some or all extensions requested by the
 client."

Since we don't support any extensions, just ignore them.

[1]: http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17#section-9
server: websocket: handle / path with default handler as documentation says
message-headers: update versioning for new APIs