Create a pip-installable aronnax PyPI package

[axch]

I am a little fuzzy on what exactly is involved in doing this. Some items that come to mind:

• [ ] Claim the name aronnax on PyPI
• [ ] When ready, upload a test package
• [ ] This probably calls for creating and maintaining package signing keys
• [ ] Download the test into a clean environment and make sure it works (e.g., by bundling the test suite with it and running it from the install)
• [ ] Perhaps automatically (for purposes of testing, it may be possible to short-circuit the actual upload-download process with something like python setup.py sdist and then testing how well unpacking that actually works)

To make this package particularly good, it would be nice to set dependency version bounds correctly. To make sure the setting stays correct, it would be nice to automatically test that the package works in a variety of environments with various versions of the dependencies (currently numpy and scipy) installed. Perhaps Travis and/or tox can help with this.