Fix encoding for geoip provider

Geoip module return ISO-8859-1 encoded strings. Special characters are broken if they are not converted to utf8 before applying a transformation (like in https://github.com/willdurand/Geocoder/blob/master/src/Geocoder/Result/AbstractResult.php#L64)

You can try with this IP : 79.120.148.112 (Bogyoszló)