modified radius function to release the pineno

modified radius function to release the pinene if the client is not authenticated properly, and modified function captiveportal_get_next_dn_ruleno to initially takes the value 2000 for the first pipeno.
Merge pull request #687 from falbertopl/master

Modified radius function to release the pinene
Enforce the checking of booting up for linkup events
On every ip change renew the hosts file
Copy/pasto does well up to some point
Do not reconfigure dhcp v6 on v4 ip address event. Only handle 6rd and 6to4 while the former is questionable if needed
Omit IP warning if HTTP_REFERER check is disabled.