Fix peristent queue restart after log cleanup (bis)
Better support for zookeeper cluster
Demo integration with ZK and ConsistencyMasterSlave
Enqueue script
Keep track of the queue last item id

Do not rely on TransactionRecorder anymore as its current consistent timestamp is computed with a delay and we need the last item id in real-time.
Merge branch 'master' into manu-demo2
Scalariform reformating
Fix persistent queue start after log cleanup
Merge pull request #27 from wajam/manu-demo2

Replication and zookeeper integration