Added MStest2 test project - to demonstrate similarities with NUnit

[seanksullivan]

Created a new Test Project, using the MSTest V2 framework, to lightly demonstrate the similarities with NUnit. All of the NUnit tests have been replicated using the MSTest V2 framework, which includes new functionality (DataRow, overrides, etc...). https://github.com/Microsoft/testfx-docs.

[jnm2]

It's up to @mike-barnett how he wants to manage the project, but as an independent observer, NUnit's Assert.That(x, Contains.Substring(x)) instead of Assert.IsTrue(x.Constains(y)) and Assert.That(x, Is.EqualTo(y)) instead of CollectionAssert and so on are a really a more intuitive and readable style and provide rich semantic failure messages. Back when I picked up NUnit, I came for the TestCaseSource and stayed for the constraint DSL because it's so nice to work with.

Which is another thing. MSTest2 doesn't have TestCaseSource, does it? If I remember correctly it has had DataRow for a really long time, but no ability to generate a dynamic number of test cases.

(Why is [ExcludeFromCodeCoverage] everywhere, especially on non-test classes? 😝)