Initial environment setup.
Add docs and a version.
Implement "requirements" setup tools command.
Make `setup.py test` run tox.

Stolen from https://testrun.org/tox/latest/example/basic.html#integration-with-setuptools-distribute-test-commands
Add coverage reporting.
Add flake8 as a style cop.
Make `setup.py test` a little more reliable.
Merge branch 'feature/implement-requirements-command' into develop