Add tests to CI

[digarok]

As per this post: https://about.gitlab.com/2016/07/29/the-basics-of-gitlab-ci/

We should start adding some sanity testing, but also consider how we want to do larger automated testing of the emulation itself.

I think for completion of this one, it would be adequate to at least run a CLI version check or something simple for feedback from the finished executable on each platform.