Mono know provides a set of testing assemblies that contain the tests to be ran in each of the supported platforms. This commit adds the following:
1. Two different runners that can be used to execute NUnit and xUnit tests.
2. The necessary glue to get xharness to run the new tests and report the results.
3. A new test that will ensure that if mono adds new tests, xharness will report failures if the tests are not run or not ignored.
Manuel de la Pena