kiji-express: EXP-347. ColumnIn/OutputSpecs were not serialized in HFileKijiScheme.

issue: https://jira.kiji.org/browse/EXP-347
review: https://review.kiji.org/r/1468
commit: https://github.com/kijiproject/kiji-express/commit/a88c731cbf0e4e919efafabd91af0af1ac9420cf