[GraphHopper] Identify an edge's tags with an encoder

[Peter]

> The information is already stored in a particular class, or do I need
> to create a new one? And in what way GraphHopper can extract these
> informations?
>

Currently you have to build everything yourself and hook a storage e.g.
into encoder.applyWayTags( OSMWay way, EdgeIteratorState edge )
We'll add a helper TagStorage in the very near future

Peter