Introduced AutoDynamicProvider - new IAutoValueProvider to support dynamic return type.
It returns stub object that intercepts "Return" calls to dynamic.
Moving dynamic stub behaviour from auto value provider to handler

Dynamic stub needs to look at call, not just type as per standard
  IAutoValueProvider implementations.
Adding another failing dynamic test

src: http://stackoverflow.com/questions/13182007/nsubstitute-mock-generic-method/
Adding more details to #75 test