Consider a better HTTP muxer/router

[jessepeterson]

http.ServeMux gets unwieldy with a large amount of routes. We sort of hobble along by using our our http.MethodMux but to consider something tiny and idiomatic like flow. I think would necessitate rewriting the middleware away from the stdlib to the common 3rd party Go muxer middleware pattern of func(http.Handler) http.Handler.

[jessepeterson]

We actually switched to flow in c2b2fdb.