Set ResolutionContext.DestinationValue when it is resolved

When a value is resolved, set it on ResolutionContext.DestinationValue so that subsequent mappers in the resolution chain can make use of the resolved value.

This is in regards to my efforts to use AutoMapper to map from a DTO to a domain model that uses DDD, see https://groups.google.com/forum/#!topic/automapper-users/_xm0A-mA03U.