Replace references to GeoTools GeoJSON with thirdpartyutils geojson

By default, Geotools GeoJSON writer truncates any coordinates to 4 decimal places. We use the Geotools GeoJSON writer to generate the upsert payload for putting shapefiles into Soda Server, and many shapefiles are specifying coordinates with 10 or more decimal places, so we lose a bunch of precision during ingest.

Due to this and other problems with GeoTools GeoJSON I am replacing it with references to our thirdpartyutils GeoJSON library, which is cleaner anyways.