tox: check setup.py too
tox: create dedicated environments for pep8 and pyflakes
pytest: add setup.cfg with ignore cmdline option
tox: remove unnecessary install command
tox: add py3 environment
tox: save coverate and JUnit reports
Ignore build output from tox
Merge pull request #14 from mgeisler/tox

tox: align file with tox.in in zpm repo