refactor(server.go) make async really async.
refactor(peer.go) use async send if possible
refactor(server.go) do not construct the string if not necessary
fix(server.go/peer.go) server.stop should stop heartbeat before close the log
chrod more clear debug info for committing
refactor make deny vote more clear
merge with master
refactor(server.go) try non-blocking send first
refactor(peer.go) clean up debugging info
Merge pull request #136 from goraft/refactor

Refactor