Merge pull request #31 from yifan-gu/dev

change setRId to setRepicaId, add something to recvPrepareReply()
prototype for recovery and clear counts before sending message
refactor phase2
remove strconv
fix bug in updateMaxInstanceNum
Merge pull request #33 from xiangli-cmu/refactor_phase2

refactor phase_2
add doc for instance doc
in progress
refine doc
Merge pull request #34 from fengjingchao/doc

add doc for instance doc
Merge branch 'dev' of github.com:go-epaxos/epaxos into dev

Conflicts:
	replica/phase2.go
Merge branch 'dev' into recovery
add RecoveryInfo
Merge pull request #35 from fengjingchao/recovery

Recovery
1. changed receiver's behaviour in terms of ballot, now it returns its own ballot; 2. write something about recvPrepareReply.