Add travis support

[jchodera]

Would be great to get this going soon!

[bas-rustenburg]

Hopefully not too much work. Only downside is that travis is not much use until we have tests that verify that the code works. Once I have the option parsers in place, I can set up some easily testable examples. One goal is to get the code at the bottom of the old models.py as a working example (though cleaned up and using the command line interface.).

[jchodera]

Hopefully not too much work. Only downside is that travis is not much use until we have tests that verify that the code works.

Good point. We'll eventually want to produce some synthetic data for this.

For now, we can at least make sure the code runs on some existing data.