kiji-bento: BENTO-78. pom.xml doesn't deploy tarball.

issue: https://jira.kiji.org/browse/BENTO-78
review: https://review.kiji.org/r/1901
commit: https://github.com/kijiproject/kiji-bento/commit/09926c2d6c3774bd2b1bfe255ec4d509ba547358