ring websocket protocol

[dspiteself]

Any interest in me implementing the ring websocket protocol. We could make a ring handler triggered by the upgrade handler. The ring handler would map HttpPrologue and Headers to a ring request and the response would expect a :ring.websocket/listener and optional headers for the upgrade negotiation. This would be more consistent and ergonomic of Clojure users. The trade off it it would require a mutable object implementing WsListener that would wrap and dispatch to :ring.websocket/listener which would be strickly more overhead for the stateless websocket use case. I expect the stateless websockets use case to be rare in the real world . Another benefit is the handler could also be used to reject unauthorized requests by not returning a listener. When a listener is not returned hirundo could throw a WsUpgradeException. One other note is because there is a handler returns a listener could close over state that would also resolve #23