kiji-model-repository: KIJIREPO-26. Determine how model-repo artifact itself is packaged.

issue: https://jira.kiji.org/browse/KIJIREPO-26
review: https://review.kiji.org/r/1132
commit: https://github.com/kijiproject/kiji-model-repository/commit/fb2bf7d258f3fe64f936b069814cdfa4c4bb525b