kiji-model-repository: KIJIREPO-37. Develop a tool to attach a freshener to the output column defined in the model environment

issue: https://jira.kiji.org/browse/KIJIREPO-37
review: https://review.kiji.org/r/1295
commit: https://github.com/kijiproject/kiji-model-repository/commit/22cc81dc4bbaf4f1d0289549e7e294200f9b5b1a