Output data in geospatial format for Leaflet

[jwestw]

Look at 3.1.a as an example of what we want to achieve: https://sdgdata.gov.uk/3-a-1/

We need to consider disclosure control at OA level. Our source data is open source so this should not be an issue.

• probably a geojson
• allow disaggregation to OA(?) level