Issue #1214: Cannot pass a int parameter to the views from ViewComponent.

#1214
Fix: Checking if the model is not null in the Copy constructor of ViewDataDictionary.
> There can be a case when the source model is absent. We should not throw in that case

*If we're constructing a derived ViewDataDictionary<int> (or any other value type), SetModel will throw if we try to set it to null. We should not throw in that case*