* Disable transitioning to new round upon 2/3+ of Precommit nils
Pull in ensureVote test function from https://github.com/tendermint/tendermint/pull/2132
* Add several ensureX test methods to wrap channel read with timeout
* Revert panic in tests
* Implement issues 2386: add synchronization in lite verify and change all Certify to Verify
* Replace make(chan struct{}, 0) with make(chan struct{})
* Parameterize memroy cache size and add concurrent test
* Refactor import order