Android rendering requires pre-loading pins

[gadzair]

My pins are generated from a network response, and so they are not available before the visibleregion changes. It still adds the pins but they are not the custom image; they are the regular pins.

[gadzair]

Ok I managed to fix it but needed to basically completely customize the renderer. As such, I felt it was out of scope of this particular github project. I decided to fork a different project and merge some of your stuff with that project to create exactly what I need and want. You can see my implementation here: https://github.com/gadzair/Xamarin.Forms.GoogleMaps