Let's not verify anymore mirror declared country consistency with the
GeoIP-detected country, because we were using some old outdated database anyway
and had a bunch of wrong results. Moreover we now have GeoIP through Mirrorbits,
managed by GNOME, which (I expect) should have more up-to-date database.
So dropping pygeoip dependency, the committed GeoIP.dat database and the check
in the gimp-mirrors.py plug-in.

Instead add a TODO in the update-mirrors.py tool which I use to verify mirrors.
We'll want to add a comparison check with what MirrorBits detect and what we
have in our mirrors.json file.