Changes to enable rolling restart of Kafka brokers

PR includes
- Kafka related changes which went into ``master`` after the ``rolling_restart`` branch was created.
- Changes to enable rolling restart of Kafka brokers.

Refer `` kafka `` community cookbook [readme](https://github.com/mthssdrbrg/kafka-cookbook/blob/master/README.md#controlling-restart-of-kafka-brokers-in-a-cluster) for some background information on the restart implementation.