fix merge conflicts
add reject prepare and refine handle prepare
Merge pull request #7 from fengjingchao/inst

add reject prepare and refine handle prepare
before merge
add rejections and tests
fix conflicts for merge
add test for handlePrepare, and panic test for handlePropose
refactor test
finish handle preaccept
before merge
Merge branch 'inst' of https://github.com/fengjingchao/epaxos into dev
preAcceptProcess and test
refactor test preaccepted process preaccept
Merge pull request #9 from fengjingchao/inst

This PR includes more lines of code in state machine and test refactoring
fix doc on prepare reply