We can detect which protocol a client speaks by analyzing the first few
bytes it sends. Then we can use HTTP for administrative & debugging tasks.

In particular HTTP right now allows to collect profiles and traces:

	https://golang.org/pkg/net/http/pprof/

and requests tracing for places where it is used:

	https://godoc.org/golang.org/x/net/trace

Even though it is a pity that such wrapping retains artifact that the
connection actually used is a wrapper connection over accepted one, the
performance impact is negligable:

	name                             old time/object  new time/object  delta
	deco/neo/go/fs1(!sha1)/zhash.go      31.6µs ± 2%      31.6µs ± 2%   ~     (p=0.897 n=28+29)