Document mulitiple PowerDNS vulnerabilities

PR: 216135
PR: 216136
Reported by: Dani <i.dani@outlook.com>
Security: CVE-2016-2120
Security: CVE-2016-7068
Security: CVE-2016-7072
Security: CVE-2016-7073
Security: CVE-2016-7074
Security: https://vuxml.FreeBSD.org/freebsd/e3200958-dd6c-11e6-ae1b-002590263bf5.html