add lua for tagtransform and docs for db import

this pr adds a some config and lua scripts to be used with osm2pgsql for routing database imports. the lua can/will also be used for direct pbf imports. ive also added some docs describing how to do this but really there is a lot more to be done in this regard.

@dnesbitt61 @dgearhart @gknisely what do you say?
ship it

On Fri, Dec 12, 2014 at 5:13 PM, Kevin Kreiser <notifications@github.com>
wrote:
>
> In import/osm2pgsql/edges.lua
> <https://github.com/mapzen/valhalla/pull/41#discussion-diff-21776978>:
>
> > +    bike_mask = bit32.bor(bike_mask, 4)
> > +  end
> > +  kv["bike_national_ref"] = nref
> > +  kv["bike_regional_ref"] = rref
> > +  kv["bike_local_ref"] = lref
> > +  kv["bike_network_mask"] = bike_mask
> > +
> > +  return 0
> > +end
> > +
> > +function nodes_proc (keyvalues, nokeys)
> > +  --we dont care about nodes at all so filter all of them
> > +  return 1, keyvalues
> > +end
> > +
> > +function ways_proc (kv, nokeys)
>
> It is the count of tags found on the given node/way/rel. I agree the
> variable name is very lacking in description and can change if you like.
> This was borrowed from the standard osmosis example style and left
> unchanged.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/mapzen/valhalla/pull/41/files#r21776978>.
>