Test in the style of xunit.

  - Some core refactoring that I think improves the design
  - A decent chunk of xunit test api's implemented.
  - Requires using TestClass base class
  - still needs more coverage for assertions
Update RunTests.Mono.Manually.sh

Added xunit tests to runner
Added XunitStyle to Mono Solution
Merge pull request #14 from jbtule/xunit_style

Add support for writing tests Xunit style