Include group in dedupe key to fix #1480

This caused the ordering to change on the pom test, but the result appears semantically equivalent. I'm still not sure it makes sense including different versions of the same dep in different scopes in the same pom, but at least now the behavior of that test is consistent whether rome is fully qualified to rome/rome or not, so that's progress. Regardless, it should fix #1480 without having to fully-qualify clojure-complete in core.project.