Added default support to DummyValueCreationSession for type Lazy<T>

Based off of the behavior that is defined for Task. Discussed in issue #358.
perhaps `should_return_a_lazy_whose_value_is_an_ifoo_dummy` or similar?

I do like the way you're performing the test, though. As a spec, I think this works much better than checking for ITaggable. Checking the dummy's instance is a good idea for dummy-verification. Thanks!