Add MaxMind local databases as a geolocation service option

PR adds method to use local MaxMind legacy database files (via the MaxMind GeoIP library), with argument to supply database path if not in current working directory.
I had a look at MaxMind website and the free version of the database they provide is called `GeoLiteCity.dat`, so maybe it would be better to let the user decide entirely the database path and filename, not only the path, what do you think?