Add UnitTests

[robertmaynard]

We need to create real unit tests for cfarm.

It looks like the easiest way forward is to use the pytest and mock packages. Combined together these should allow us to have infrastructure for tests.

We need to add a testing_requirements.txt that lists pytest and mock, so that other developers can run the tests easily.

Lastly we should add travis CI support to the project, so that we can easily verify our project.