kiji-schema: SCHEMA-887. Cassandra integration test should use only one Cassandra node.

issue: https://jira.kiji.org/browse/SCHEMA-887
review: https://review.kiji.org/r/2078
commit: https://github.com/kijiproject/kiji-schema/commit/8a94088b6b668b5ed0d54d0204d9c39f3795bc82