raft: set none to be 0
etcdserver: fix testServer
raft: use const firstId to track ids
raft: set From of local message to be local id
raft: use [1,n] as address list for raft state machines
raft: use raft helper function in testing
raft: remove vote with default value
raft: more descriptive panic info
raft: set propc, readyc to be nil before run loop
etcdserver: remove useless sleep

etcdserver.Do will block until there exists leader
raft: refine plus assignment
Merge pull request #1042 from unihorn/118

raft: set none to be 0