rightscale/zookeeper repository overview

Copied and modified from official repo (https://hub.docker.com/_/zookeeper⁠ && https://github.com/31z4/zookeeper-docker⁠) that supports 2 additional ENV config options of ZOO_AUTOPURGE_RETAIN_COUNT and ZOO_AUTOPURGE_PURGE_INTERVAL, and additional wrapping of own entrypoint script which would populate the env from consul/vault.