Better Testing for kitchen-dokken

[dwmarshall]

See #199 for the difficulties I've encountered trying to get Travis testing to work. The larger question is whether that's the correct testing to be doing. The current test is more of a convoluted functional test that seems to have been written to run in some previous development environment. It might be possible to get docker-in-docker-in-docker to work, but what would that tell us? In some ways, a successful test says more about test-kitchen than kitchen-dokken.

My idea is to survey other kitchen-* gems to get a sense of the current testing practice, at least for unit testing. Functional testing should be spread among a variety of platforms and a reasonable mix of Chef versions.

I hope that I'll have time to do this soon (especially because I want to immediately fork kitchen-dokken to kitchen-podman), but I won't think badly of anyone who picks this up before I do. One thing to note is that the method for determining local docker should check for a URI of unix:// in addition to tcp://.

[marcparadise]

Thanks @dwmarshall, I also see that you have some WIP on #201, but nothing that addresses the meat of this issue so far. Is that something you still plan to include in that PR?