Enhanced unit tests for code generators to compile the generated code, l...

...oad, instantiate, execute, and re-generate from compiled result.

Fixed a few issues discovered while running the enhanced tests.
This path is specific to our build. In VS 14 using the kprojs, the path will be different. In fact, there may not be files on disk at all if the tests are run without building first.

You should be able to get to a MetadataImageReference for the in-memory assemblies using the ILibraryManager service.