Geoloc

A geolocation service.

I don't know if the function and features must be given like this, as parameters.
And all these "logic" must be really in the service ? I think that's good like this but I'm not sur.

Other things, Does this services must have a "remove" function to unbind all created events ?

Thanks to review.
I'd move this to the example. And I'd use a `change:position` listener for clarity:

```js
geolocation.on('change:position',
    /**
     * @param {ol.ObjectEvent} e Object event.
     */
    function(e) {
      positionFeature.getGeometry().setCoordinates(geolocation.getPosition());
    });
```
```