refactored ZkProxy and support classes
Kafka now has its own configuration key that falls back to the Zookeeper key if not found
refactored the Zookeeper module (separated delete and delete recursively)
removed unused property
Merge branch 'develop' into feature/mongodb

* develop:
  removed unused property
  refactored the Zookeeper module (separated delete and delete recursively)
  Kafka now has its own configuration key that falls back to the Zookeeper key if not found
  refactored ZkProxy and support classes