Unit testing and CI and codecov

[DominiqueMakowski]

This package could definitely use continuous integration with Travis and Appveyor, to easily detect breaking updates. This goes along with testing coverage (such as codecov).

[tszanalytics]

Ok, no idea how to do that at present (trying to finish up a paper on predictive model selection at the moment). I think the few tests that are currently in the package need updating for 1.0 anyway, and many of the current functions have no test.