Issue #1206 - DefaultBodyModelValidator throws if get accessor throws.

Issue #1206
Fix: Introducing ExcludedValidationTypes in MvcOptions so that the user can exclude types which throw during Validation.
It does seem like you get different behaviors depending on if you call `Validate` (no validation at all) or if we encounter the type as part of the object graph (shallow validate). Maybe move it inside so we do shallow validate? In which case we should make it explicit in Options that this means that we will validate an item of the specified type but not it's properties.