Split Constantly out into its own project.

This does the following:

- Updates code references
- Adds Tox, for py26, py27, pypy, coverage and pyflakes
- Adds a basic README and LICENSE
- Adds a setup.py
- Adds versioneer
The distutils docs says "a list of strings or a comma-separated string".

"enum" might be useful here, too, if the goal is to help people doing searches find this library.