Wrapped response does not expose http.Hijacker interface

[hlubek]

Some of the special interfaces like http.Hijacker are not exposed using the wrapped response writer.

It would be great to implement something like https://github.com/gorilla/handlers/blob/941e2d87ae774cb93574f1af30684ed9bfe24271/logging.go to implement interfaces for the wrapper if the original response implemented them.

The current implementation prevents Websocket upgrades, so we need to create our own version of it.

[tj]

ahh cool I'll try to look into adding that soon! I haven't used websockets in ages