Switch NUnit to VS Unit Testing

[activescott]

I loathe to do this on one hand because I always thought that MSFT should support and improve NUnit rather than creating another unit testing tool (at least be completely compatible with it). However, I've found NUnit is now unbearable to use with VS 2015 and .NET frameworks. It is extremely difficult to figure out that you need to install several add-ons and weird packages just to see unit tests and even once installed it regularly doesn't show all the unit tests.
Since one of my goals is to keep lessmsi easy to get going with I've decided to remove nunit and use the new lowest common denominator for unit testing which appears to be VS/MS unit testing.