Update to January GeoIP2 database
My geoip-2018-01-05 branch contains the updated
geoip6 files with IPv4 and IPv6 ranges and is supposed to be merged into maint-0.2.5 and all other relevant branches.
(I'm never sure what to pick for milestone and keywords here, so I'm copying those fields from past tickets. Please update those fields if you want me to fill in different versions in future tickets. Thanks!)