Switching from Google to ESRI and from ggmap to maptiles as the supplier of the earth images, after google changed their API to be less friendly to this kind of thing.
This version tries to adapt to the changes to the google maps API. For this to work seamlessly, ggmap needs to be working. For more information on that check the ggmap github page. For more information on what google is doing to make money with google maps see their page on the changes.