Suppress warnings and output on tests

[gaffney2010]

When we run all the unittests, it prints out stuff besides just the test results. I think it would be nice if this wasn't there. It would be cleaner. And unexpected new warnings would more obviously surface. Specifically:

test_memoryone and test_memorytwo produce UserWarnings that we can fix or suppress. test_human produces outputs; these can probably be silenced.