* server/cors.go renamed to http/cors.go
* all CORS code removed from Server and PeerServer
* Server and PeerServer fulfill http.Handler, now passed to http.Serve
* non-HTTP code in PeerServer.Serve moved to PeerServer.Start
* -trace flag controls whether or not to enable metrics-gathering
and the /debug/* HTTP endpoints
* -graphite-host flag controls where metrics should be sent
* timer.ae.handle metric tracks execution time of AppendEntriesRequest