Use datahub CDN endpoint for NLCD and SSURGO tiles
Use datahub CDN endpoint for NLCD and SSURGO tiles

Instead of serving tiles directly from Amazon S3, use the new CDN
enabled datahub endpoint.

See also: https://github.com/azavea/azavea-data-hub/pull/37

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