Add a changelog
Add a setup.py file
Put the tests under hawk/tests
Minor style changes to comply with PEP8.

- Removed spaces at the end of the lines.
- Added python-like documentation which can be understood by Sphinx.
- Added 2 blank lines between classes and only one between functions.
- Capped the lines to 80 chars max.
Merge pull request #5 from ametaireau/minor-changes

Minor enhancements wrt style & packaging