Sensor.community import group sensor_id by location

[n11ik]

Assume: Sensor community stations are uniquely determined by (lat, lon).
Sensor.community: Sensor is uniquely determined by sensor_id.
Luftdaten.at: Sensor cannot be uniquely determined.

To be able to uniquely determine the imported sensor we could create a table: (station_id, measurement_id, sensor.community.sensor_id)
Evaluate if we should create this table.

Import measurement:

1. Check if station exists (lat, lon)
   1.1 NO create station
2. ADD measurement to station
3. ADD entry in table (station_id, measurement_id, sensor.community.sensor_id)