add timezone lookup

[tmm1]

Most of the maxmind libraries provide a timezone api, which is based on data from http://www.maxmind.com/timezone.txt.

For example, the php library generates the following lookup tables from that textfile: http://geolite.maxmind.com/download/geoip/api/php/timezone/

[tmm1]

The URL should be http://www.maxmind.com/timezone.txt