Code review comment for lp://qastaging/~andreserl/maas/maas_systemd_1.7

Thanks! This addresses most of my remarks in https://code.launchpad.net/~maas-maintainers/maas/packaging_add_systemd_support/+merge/251829 , except one which I repeated below. The units look good to me now. (Note that I didn't test any of this, I haven't worked with setting up MAAS yet. But with cloud images and vivid being systemd by default now I suppose you can test this easily in CI even?)