Responses should be in geojson format

[hampelm]

With this, we'll be able to serve geodata in a consistent format. This'll also let us take advantage of 2dsphere indexes in Mongo 2.4, which support more geometries.

This will require changes to the dashboard and mobile client.

From the GeoJSON spec:

• A feature object must have a member with the name "geometry". The value of the geometry member is a geometry object as defined above or a JSON null value.
• A feature object must have a member with the name "properties". The value of the properties member is an object (any JSON object or a JSON null value).
• If a feature has a commonly used identifier, that identifier should be included as a member of the feature object with the name "id".

From the MongoDB 2dsphere index docs:

{ <location field> : { type : "<GeoJSON type>" ,
                       coordinates : <coordinates>
} } 

[hampelm]

We'll also need a migration script in maintenance.