[iOS7] Implements custom callout view controller management in CKMapAnnotationView for iOS7.

* The size and position of the callout as well as the animation is not perfect yet. It is more complicated than before as callout views are now presented in internal map popover implementation and customizing the callout view & size is delicate. We'll get more development on this later if the behaviour is not acceptable or if we get refused for submission as we had to do it by the back door ...