kiji-modeling: EXP-285. Change access modifiers to 'kiji'.

issue: https://jira.kiji.org/browse/EXP-285
review: https://review.kiji.org/r/1336
commit: https://github.com/kijiproject/kiji-modeling/commit/bbedf1e5fe0a207df87548e785e0e7b417d80292