* Mention python 3 support in setup.py
* Build universal (py2 and py3 compatible) wheels
* Mention Python 3.3+ support in docs
* we work on python 3.6 too
1. --cover-tests, to make sure every test is run, helped to find
broken determine_account tests
2. fix determine_account test
3. unittest.main() # pragma: no cover
4. bump coverage
coveralls.io always reported higher coverage, because it also looked
at test files.