kiji-schema: SCHEMA-692. ZooKeeperClient should block while connecting

issue: https://jira.kiji.org/browse/SCHEMA-692
review: https://review.kiji.org/r/1751
commit: https://github.com/kijiproject/kiji-schema/commit/d3dea5a048ef1d20f7e78932ff2df219d4c75f22