Adds a junit test integration test, including coverage options.

(Is cobertura working? I don't see any output in the cobertura reports.)

Testing Done:
ci is running.

Bugs closed: 675

Reviewed at https://rbcommons.com/s/twitter/r/1161/
Sync of https://github.com/pantsbuild/pants/commit/3e589a5b332a8fdfd379f69584afbe4ae333fa45