Added testing configuration for Python 2.6, 2.7, 3.1, 3.2, 3.3, 3.4

This commit adds a testing configuration for Python 2.6, 2.7, 3.1, 3.2, 3.3, 3.4 (Python 3.0 isn't included as it's not part of my Mac's port repo) using the tox tool. The tests all pass so that means the package can include the classifiers Python 2 and 3. While everything already worked without this commit, this config allows you / us to check that routinely.