Feature request: Render Counties layer on Mapbox

[asaprahul]

Right now, we support three kinds of geolocation rendering on the Map.

1. Zipcode (zoomed in)
2. Zipcode (zoomed out)
3. Cities (basically circles around the lat/long of city center)

We need to be able to render counties.

Found a county-level polgyon geolocation data here and it looks promising:
https://github.com/jackparmer/mapbox-counties/blob/master/us-counties.json
(thanks to @jackparmer)