Merge pull request #5 from fengjingchao/dev

finish simple propose
Merge pull request #6 from yifan-gu/dev

add stupid test
Merge pull request #7 from yifan-gu/dev

not exported
finish simple recvPreAccept
Merge branch 'dev' of github.com:go-epaxos/epaxos into dev
Merge pull request #9 from fengjingchao/dev

finish simple recvPreAccept
before merge
sendaccept and acceptreply