let users repair Null Island records

[burritojustice]

While importing a CSV, if the lat/lon fields contain 0,0 or null, we import it but tag it with null_island.

After we upload, and the user has a chance to inspect the Null Island records, they may find fields that they could use to geocode these records visiting Null Island.

• There may be a points field that the user may not have been aware of that we can use.
• If there's an address field, we could let the user specify it and geocode it (though that may be a local address with no city, state, county…)

We should collect and consider the various cases and figure out how to do a processing run to get those records off Null Island.