Test and record for ipv6 status for different hosts in Nagios

For each CE and SE, save also the ipv6 status - currently as 0:HostHasipv6address, 1:HostHasOnlyipv4Address and -1:NotAValidHost.

The xml feed from this can be used to populate a web page for the ipv6 WG to display the statuses of the different sites as seen by LHCb.