minor cleanup and blacklisting pytest 3.3.0

[mattsb42-aws]

• Blacklisting pytest 3.3.0 (pytest 3.3.0 breaks some of our tests #125) and adding tests to make sure we catch it if pytest breaks in this way again. 3.3.0 parametrized node IDs are not ACSII escaped :: breaks PYTEST_CURRENT_TEST in Python 3 pytest-dev/pytest#2957
• Fixing some minor formatting issues I missed in fix for Python 3.5.0/3.5.1 compatibility issue #118