unit test helper classes. Changed calls from old TypeFinder to new TypeFinder2. Created benchmark unit
tests to test speed differences between them.
Fixes: 30946 - IOHelper with HttpContext issue
Fixes: 30945 - AppCodeFileExtensions issue with UmbracoSettings
Had to fix the ApplicationTree and Application classes to lazily call the Cache method
(which is no renamed to EnsureCache) so that we could set the config location in the unit tests.
This should also improve performance a teeny bit and allow for better error handling if required.
