kiji-schema: SCHEMA-891. Configurations in unit tests should include the external zk quorum if specified.

issue: https://jira.kiji.org/browse/SCHEMA-891
review: https://review.kiji.org/r/2086
commit: https://github.com/kijiproject/kiji-schema/commit/da2a4b969f34497f1f45afa5380f6bec5bdd622a