Unit tests!

[brabebhin]

A few weeks ago I gave unit testing for UWP another chance, and I have to admit, Microsoft really did get their things together and made this work in a reasonable manner. Tests are now detected upon build, it is easy to run & debug them, and they provide the entire environment of an UWP, so a lot of winRT APIs work without the need to mock them, making integration testing very easy.

Perhaps we should explore adding unit tests to this project. As a medium term project.