Download MaxMind's geoip file over https.

If the cert turns out to be invalid or if wget is otherwise unable to
verify it, it's going to return an error and not download the file for us.

Spotted by nickm.

src/config/mmdb-convert.py

@@ -418,7 +418,7 @@ def dump_tree(entries, node, dump_item, prefix=""):
 
 GEOIP_FILE_HEADER = """\
 # Last updated based on %s Maxmind GeoLite2 Country
-# wget http://geolite.maxmind.com/download/geoip/database/GeoLite2-Country.mmdb.gz
+# wget https://geolite.maxmind.com/download/geoip/database/GeoLite2-Country.mmdb.gz
 # gunzip GeoLite2-Country.mmdb.gz
 # python mmdb-convert.py GeoLite2-Country.mmdb
 """