kiji-express: EXP-445. Fixes malformed xml in the archetype pom.xml

issue: https://jira.kiji.org/browse/EXP-445
review: https://review.kiji.org/r/1893
commit: https://github.com/kijiproject/kiji-express/commit/a10d5b34fd7e9c3b9217b15a2f3f6076ddeb6e1e