Merge pull request #23 from yifan-gu/dev

After discussing, agree on merge
fix setting Id in incrementing ballot
rename r.N to r.Size
Merge pull request #27 from fengjingchao/dev

fix setting Id in incrementing ballot
refactor(phase1.go) add findDenpenencies
refactor
refactor
docs
add deps.go
refactor deps.go
Merge pull request #28 from xiangli-cmu/dev

rename r.N to r.Size
change name
refactor
Merge pull request #29 from fengjingchao/dev

change name
merge and refactor
merge master
Merge pull request #30 from xiangli-cmu/dev

refactor
change setRId to setRepicaId, add something to recvPrepareReply()