rewrite ballot
Merge pull request #22 from fengjingchao/dev

rewrite ballot
Merge branch 'dev' of github.com:go-epaxos/epaxos into dev
fix ballot compare
fix compare on 32bit arch
Merge pull request #24 from fengjingchao/dev

fix ballot compare
Merge branch 'dev' of github.com:go-epaxos/epaxos into dev
update for new ballot