add some tests for preAcceptedProcess, need more
add tests for preAcceptedProcess, completed, add `update seq' in handlePreAcceptReply
Merge branch 'dev' of https://github.com/yifan-gu/epaxos into inst
add initInstance and updateInstance and refine test
refactor test and change getcopy to clone
Merge pull request #22 from fengjingchao/inst

Add more test and refactor code