Added a way to geocode by components

[lampkap]

Hey, thanks for this package!

I added this PR because I needed to geocode a location to coordinates but I only have a postal code and a country. This can be done with the geocoding API using components. So I added this functionality to your package.

To use geocoding with components, you can do the following:

Geocoder.from('components', { postal_code: '1000', country: 'BE' }).then(json => ...);

Any feedback is greatly appreciated!

Thanks!