kiji-schema: SCHEMA-875. Revert binary incompatibility introduced in SCHEMA-826

issue: https://jira.kiji.org/browse/SCHEMA-875
review: https://review.kiji.org/r/2051
commit: https://github.com/kijiproject/kiji-schema/commit/2161087ffdb675a2b6e75defab3e5ec1d0d04615