Replace AnyObject with Any

[jjatie]

This is in line with how Objc interfaces are now imported

[liuxuan30]

despite the weird indent here by github, why we use Any and again cast to AnyObject later
I assume using AnyObject is fine

[jjatie]

This is to align with how ObjC APIs are imported into Swift. More info here: https://developer.apple.com/swift/blog/?id=39

We were only using AnyObject in the initializer because of weird objc interop.

[liuxuan30]

oh no. I'm using Dash and cannot even found Any type. this kind of information is not easily to be aware of in my daily work..

[liuxuan30]

@jjatie why would we change to Any here? I checked the doc:

You use AnyObject when you need the flexibility of an untyped object or when you use bridged Objective-C methods and properties that return an untyped result. AnyObject can be used as the concrete type for an instance of any class, class type, or class-only protocol.

so it seems the old AnyObject in this PR fits the scene. But using Any seems wilder, and unnecessary to me