[Sprint 39] [master] XD-2333 Add Kafka integration test

  - Add kafka test support class that checks for kafka server availablity on localhost
     - This uses zk server available on default connect string `localhost:2181`
  - Add test for verifying kafka source and sink
     - having both the source/sink on the same test case will make sure the topic that
gets the data by kafka sink is actually read by kafka source
@garyrussell here I check zk server along with if the zk has entries for kafka brokers(though that doesn't check if the broker is also from localhost). But, I like your approach and will use it here.