Be quiet about coverage locally.

I certainly don't have a strong opinion about this, but I'm not a fan of the extra chatter in my test runs about coverage (particularly the jarring yellow **Outside of Travis, not sending data** stuff that makes me think I accidentally left a spec pending).

This PR makes it go away locally. Anybody care one way or another? You can still run it as-is by passing `COVERAGE=true` in your rspec command if you really want to check the coverage locally yourself. If this does get approved I will probably do the same thing in API.