Add support for mapbox simplestyle for GeoJSON
@jonasdn
Submitted by Jonas Danielsson Link to original bug (#757144)
Description
As specified here: https://github.com/mapbox/simplestyle-spec/
Should be investiged if we can do it in geoJSONSource.js or if we have to get into the geojson-vt/ code from mapbox. Maybe we can just look in the tags object?