create geojson endpoint

[perryr16]

Similar to the public feed endpoint, create and endpoint that exposes geojson data for a group of properties. The inventory list action export -> export geojson has some existing functionality that could be leveraged.

for an example, go to geojson.io and paste the .geojson data from the export.

• Property Footprint should be included, and is where polygon info lives
• consider pagination
• specify cycle
• endpoint: public_geojson