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?
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.