Add viewDidChange to update zoom and center

Hi Gabe,

I wanted to be able to set the zoom and center of my mapView at the same time. But with the current implementation `isMoving` was blocking the center pan. I also found that chaining `setZoom` and `panTo` doesn't necessarily take you to the correct location.

This allows me to do `view.setProperties({zoom: X, center: [lat, lng]})` while also still being able to just set zoom or center individually.