ENH: Quieter testing

This makes it so that the coverage doesn't print at the end of each test. It's not very useful to have it. Coveralls is way better. And if we want to look on our local computer, we can now do `make nose_coverage &&  make coverage_html` and the coverage results will be put in interactive form in the `htmlcov` directory.

Ready for review/merge.
This was causing some intermittent Travis failures (and on my machine), so I removed it. There are plenty of other places we look at these properties, probably more carefully than this, so we don't need it.