Update travis file
Hi,
I updated the travis file to test on more python versions (python 3.4, 3.5 and 3.6) and fixed the test URLs: https://github.com/Rafiot/python-rt/tree/travis
Feel free to merge it directly from there or if you want me to do a pull request, please allow me to fork the project :) (I get an error message saying I reached my limit).
Well done with the API, it seems to be the only supporting properly python3.
Cheers, Raphaël