Add geojson boundaries to layouts

Should / could plot info, e.g. from https://brapi.workbench.terraref.org/brapi/v1/studies/6000000034/layouts, contain geojson (?)

Or could update locations: https://github.com/terraref/brapi/blob/master/api/locations.py based on v2.x https://app.swaggerhub.com/apis/PlantBreedingAPI/BrAPI-Core/2.0#/Location