kiji-model-repository: EXP-420. Update to scala 2.10

issue: https://jira.kiji.org/browse/EXP-420
review: https://review.kiji.org/r/1700
commit: https://github.com/kijiproject/kiji-model-repository/commit/7b9a0cab7e290d4f65b52e70b3d9dd5c32c82ea2