Use generic names for layers. Add Google Terrain.
Use generic names for layers. Add Google Terrain.

* Replaced branded layer names with generic names.
* Add the Google Terrain layer as an option.

Refs #696

kdeloach/model-my-watershed,lliss/model-my-watershed,project-icp/bee-pollinator-app,project-icp/bee-pollinator-app,WikiWatershed/model-my-watershed,lliss/model-my-watershed,kdeloach/model-my-watershed,project-icp/bee-pollinator-app,kdeloach/model-my-watershed,WikiWatershed/model-my-watershed,kdeloach/model-my-watershed,WikiWatershed/model-my-watershed,project-icp/bee-pollinator-app,lliss/model-my-watershed,lliss/model-my-watershed,kdeloach/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,lliss/model-my-watershed