Add label

add a new field on some pt object: label

the label is meant to be a better name. It contains for the stops and the poi the city:
for the administrative regions, it contains the range of the postal codes.

Also fix the name of the places to get the label if is exists.
```
from": {
    "embedded_type": "stop_area",
    "id": "stop_area:SCF:SA:SAOCE87543009",
    "name": "gare d'Orléans (Orléans)", <-------- label of contained object
    "quality": 0,
    "stop_area": {
        "administrative_regions": [
            {
                ...
                "id": "admin:45234",
                "label": "Orléans (45000)", <---- name of the city + postal code
                "level": 8,
                "name": "Orléans",
                "zip_code": "45000"
            }
        ],
    ...
        "id": "stop_area:SCF:SA:SAOCE87543009",
        "label": "gare d'Orléans (Orléans)", <------ name of the stop area  + city
        "name": "gare d'Orléans",
        "timezone": "Europe/Paris"
    }

},
```