SCHEMA-418. ZooKeeperClient logs are too verbose

Lowers logging verbosity of ZooKeeperClient from info to debug.

issue: https://jira.kiji.org/browse/SCHEMA-418
review: https://review.kiji.org/r/643
SCHEMA-419. Bogus log statement in FormattedEntityId

Fixes log statement in FormattedEntityId.

review: https://review.kiji.org/r/633
issue: https://jira.kiji.org/browse/SCHEMA-419
contributed-by: jeffkole (Jeff Kolesky, jeff.kolesky@gmail.com)
SCHEMA-409. Add caching of AvroCellEncoders to table writers.

issue: https://jira.kiji.org/browse/SCHEMA-409
review: https://review.kiji.org/r/623
SCHEMA-401. Update cell write path validation

issue: https://jira.kiji.org/browse/SCHEMA-401