Nullability Qualifiers and Primitive Generics

Hi, I'm really glad you did this. I was also working on porting Advanced NSOperation to Objective-C and you'd already done it and found it very helpful. 

Mine isn't as complete but I do use Nullability qualifiers as described in:

https://developer.apple.com/swift/blog/?id=25

Do you plan on adding these? Maybe if I can find a bit of time I could fork and them to yours.
