Geocoding improvements

```
tools.geocoding delegates finding a geocoder to geopy.

Geocoding results are handled as geopy.location.Location objects,
and altitude is added to shapely.geometry.Point objects.

None results from geocoding results are handled better.

geopy is upgraded to >=1.1.0.
```

I saw this is being used, and thought I'd provide a better interface. Let me know if I've misunderstood something about the use or you have other feedback.