Add tox test-runner, and very basic tests

[asheesheventbrite]

This test suite exists so that we can verify the success of a pull request submitted to this package that supposedly gives us Python 3.x support.

We would do better to have a more serious test suite, but this is noticeably better than nothing, as it also provides a tox.ini which will enable us to run the test suite on multiple versions of Python easily.