Add missing python backend plugin dep on the old py commands.

Fixup listtargets test - use uniform address.spec.

Also do the same for filemap as a cleanup sweep on
  https://rbcommons.com/s/twitter/r/537/

Testing Done:
$ ./build-support/bin/ci.sh

Travis went green: https://travis-ci.org/pantsbuild/pants/builds/27698663

Bugs closed: 239

Reviewed at https://rbcommons.com/s/twitter/r/540/