Sample TOML config for osm2pgsql import

[ARolek]

This issue is a follow up to to go-spatial/tegola#144. The goal is to setup an example tegola config file which uses the schema generated by osm2pgsql.

[ARolek]

@dBitech @simonpoole. We can use this issue to continue the discussion with osm2pgsql. I'm going to reorganize this repo so it's better structured to support instructions for the various import tools and schemas. Thanks for the help.