Merge pull request #185 from m1ch1/master

Netty: Close incoming connection on clear()
Make batch size configurable.
Merge pull request #186 from EasonLiao/config_batch_size

Make batch size configurable.
Remove round robin election.
Merge pull request #184 from EasonLiao/remove_round_robin

remove round robin election
Some cleanups on code.
Some changes on doc.

1. Fix the url(from branch to version) problem.
2. Add workflow git pic.
Merge pull request #188 from EasonLiao/doc

Some changes on doc.
Change quorumSet to quorumMap.
Merge pull request #192 from EasonLiao/fix_name

Change quorumSet to quorumMap.
Expose ZabConfig to user.
Merge pull request #187 from EasonLiao/cleanup

Expose the ZabConfiguration to user