IPv6 data missing from latest/metadata info

When querying the latest/metadata API, IPv4 data ( local-ipv4 and public-ipv4 ) are available but ipv6 data is not.

3 lines to be added:

/usr/lib/python2.7/site-packages/nova/api/metadata/base.py
        fixed_ips = self.ip_info['fixed_ips']
        fixed_ip = fixed_ips and fixed_ips[0] or ''

        # JvB added
        fixed_ip6s = self.ip_info['fixed_ip6s']
        fixed_ip6 = fixed_ip6s and fixed_ip6s[0] or ''

        fmt_sgroups = [x['name'] for x in self.security_groups]

        meta_data = {
            'ami-id': self.instance.ec2_ids.ami_id,
            'ami-launch-index': self.instance.launch_index,
            'ami-manifest-path': 'FIXME',
            'instance-id': self.instance.ec2_ids.instance_id,
            'hostname': hostname,
            'local-ipv4': fixed_ip or self.address,
            'local-ipv6': fixed_ip6 or '', # JvB added
            'reservation-id': self.instance.reservation_id,
            'security-groups': fmt_sgroups}

It would be useful to have the subnet mask info available as well, but this would involve more changes and perhaps some discussion about naming conventions