instantiateInitialController return type should be scoped by enclosing module

[nhojb]

This is an issue if the storyboard has the same name as the initial controller e.g.

struct Storyboards {
    struct FooViewController: Storyboard {
        static func instantiateInitialController() -> FooViewController {
            return self.storyboard.instantiateInitialController() as! FooViewController
        }
    }
}

Opps! instantiateInitialController returns a Storyboards.FooViewController, not a Module.FooViewController :-(

The obvious work-around is not to name storyboards using the same name as the initial view controller. However for simple storyboards this can be a convenient and natural naming.

Looks like natalie just needs to parse the "customModule" attribute for "viewControllers" in the storyboard xml.