validate-type-resolution-233

Related to #233 

* Added better typeresolution for config and serialization.
instead of checking `Type.GetType` for `null` result, that is now handled in a helper method with a consistent error message.

Questions:
* What should the errormessages be?
* Where should the helper methods live? currently located in `TypeExtensions` but these are not extension methods, 
* there is some inconsistent behavior on failed resolution, throw, log, ignore, see todo's