[BF] whois.bgpmon.net no longer available

[listerr]

whois.bgpmon.net is no longer available, change default prefix whois to whois.radb.net.

In addition to the above, I have:

• ensured all relevant template output is escaped to avoid XSS attached with <?= $t->ee( $data ) ?> or equivalent.
• ensured appropriate checks against user privilege / resources accessed
• API calls (particular for add/edit/delete/toggle) are not implemented with GET and use CSRF tokens to avoid CSRF attacks

[nickhilliard]

lgtm. radb is probably the most appropriate DB to use after bgpmon (https://irr.net/registry/)