Add name of geofabrik region to coverage geojson

[Hagellach37]

When using the geofabrik name to create a task in realtimeosm, the geometry will be generated as geojson.

We should add an attribute geofabrik_name to this geojson. This will help us to identify which tasks have been created with geofabrik names.

[masain]

the name of the geofabrik extent is already included:

"coverage":{
    "type":"Feature",
    "geometry":{"type":"Polygon","coordinates":[[]]},
    "properties":{"name":"north-america"}
    }