Added ViewModelBaseTests class
Minor code cleanup (analysis fixes)

- Changed DLLs to be CLSCompliant
- Added SuppressMessageAttribute to a few methods that had code analysis
warnings but could not be changed
- Extracted nested classes from Skippable
- Changed ViewModelBaseOfT to have protected constructors (it's an
abstract class so it should not have had public constructors)
- Added CustomDictionary.xml