Packaging

Shit just got real.

This is a cleanup to get us ready for our first RC release.

- make tests a module
- un clutter requirements setup
- migrate to setuptools
- add tox
- add pytest.ini so we don't have to duplicate command line flags all over the place
- read in long_description from README.md
- add .coveragerc file to ignore tests module
- notes on PyPy version....