kiji-model-repository: POM-32. Add references to Curator in root-pom.

issue: https://jira.kiji.org/browse/POM-32
review: https://review.kiji.org/r/1802
over-the-shoulder-reviewers: ['lsheng']
commit: https://github.com/kijiproject/kiji-model-repository/commit/20e6def2bc3e25e6420306e2172c6f6350e64f59