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.
Roslyn all the things! :wink: I found some [examples of compiling](http://roslyn.codeplex.com/SourceControl/latest#Src/Samples/CSharp/APISampleUnitTests/Compilations.cs) under the Samples folder in their repository.