.Net Core Tests

[nemec]

Branch: dotnet-core

One of the features of the new system is the command dotnet test which executes the test cases for a project. Before merging the dotnet-core branch into master I want to make sure we can run our tests on it.

This may help: https://xunit.github.io/docs/getting-started-dotnet-core.html

[nemec]

Needed to fix some additional tests in ecb9e64 but the tests now build completely in .Net Core. The dotnet-core branch has been merged into master.