Add event for order change of Globe Layer

[ylvaselling]

Is your feature request related to a problem? Please describe.
In order to update the UI automatically on different browser windows we need an event to tell the UI that the layer order has been updated. For example, if you have a browser window open and you change the order in the native application, the order doesn't update in the browser window.

Describe the solution you'd like
Add an event for the reordering of layers.

[micahnyc]

Maybe it would make sense to combine the LayerAdded and LayerRemoved with this LayerReordered, and we can call it GlobeLayerUpdate or something? Then it could have the info + type.