Geoip datadir support

I added a parameter to specify where the .dat files for maxminds geoip databases should be looked for. By default it is set to /usr/share/GeoIP/ as you previously had, so it will probably not break backward compatibility.

I also noted that when using pygeoip you don't have the key 'region' in when performing a lookup, but you have region_name. I did not further investigate, but I believe this is a quirk that has to do with the usage of GeoIP over pygeoip.