kiji-rest: REST-117. Add logback configuration and maven enforcer for cleanup.log.

issue: https://jira.kiji.org/browse/REST-117
review: https://review.kiji.org/r/1749
commit: https://github.com/kijiproject/kiji-rest/commit/bbb84ab93dda52c78c1fa0959d0aa4a2116981e9