support python 3.x

[JohnMurray]

It would be nice if the user didn't have to worry about what version of Python they are running to use the tool. Python 3 is the future (right??) so we should support it. In addition, this is meant to be used as a general tool on someone's computer, not as something that needs to be run inside a virtual-env or some nonsense.

The easiest solution may to just edit the .travis.yml file and fix the test errors. We may want to get our test-coverage up before attempting this. :-)