Helps determine if valid database exists and which version it corresponds to.
On startup the legacy connectionstring is used if one exists, so its not ignore but rather reconfigured.
Relates to U4-1520.
Adding a MediaTypeMapper similar to the ContentTypeMapper, but type specific.
The PetaPoco IMapper implementation is removed as its no longer needed.
Updating a few unit tests, as the Where clause is now correctly formatted.
Adding unit tests for the new ExpressionHelper and MappingResolver classes.