Add a zookeeper cluster

[shazChaudhry]

I would like to add a zookeeper cluster in swarm mode. These repos / blogs / issues might be a good candidates to learn from:

• https://github.com/itsaur/zookeeper-docker-swarm
• https://stackoverflow.com/questions/39271464/start-solr-cloud-on-docker-swarm-1-12-without-zookeeper/39282268

Zookeeper cluster is needed to run Solr in cluster configuration

[shazChaudhry]

This StackOverflow was useless: https://stackoverflow.com/questions/39271464/start-solr-cloud-on-docker-swarm-1-12-without-zookeeper/39282268

• I used the example provided and all replicas are stood up in stand alone mode; not in a cluster mode
• I asked a question but to my annoyance, they deleted my question

An issue has been logged at https://github.com/itsaur/zookeeper-docker-swarm/issues/12; asking how to suppress Closed socket connection INFO logs