fix doc on prepare reply
finish committed optimization
Merge pull request #15 from fengjingchao/inst

Commits ready for merge
Merge branch 'master' of github.com:go-epaxos/epaxos
add info and recovery info in new instance
add original ballot in prepare message
before merge
change starting epoch to 1 and renew entering new states.
add some tests for acceptedProcess
add some tests for acceptedProcess