kiji-schema: SCHEMA-689. Deadlock occurs in KijiBufferedWriter when Zookeeper connection fails

issue: https://jira.kiji.org/browse/SCHEMA-689
review: https://review.kiji.org/r/1752
commit: https://github.com/kijiproject/kiji-schema/commit/17db6a9609cdaabbf18d30affe62152cfd08e10f