#61 OpenStreetMap : streetName is sometimes undefined

In some specific cases, nominatim does not returns 'road' in address but 'cycleway' for the streetName.

Ex : http://nominatim.openstreetmap.org/reverse?format=json&lat=48.8635556&lon=2.332988&zoom=18&addressdetails=1

I fix that by adding this in the lib/geocoder/openstreetmapgeocoder.js, line 58

```
'streetName': result.address.road || result.address.cycleway,
```

As this, cycleway is used as a fallback for streetName.