Document multiple security advisories for Moodle

Security: CVE-2016-3729
Security: CVE-2016-3731
Security: CVE-2016-3732
Security: CVE-2016-3733
Security: CVE-2016-3734
Security: https://vuxml.FreeBSD.org/freebsd/8656cf5f-4170-11e6-8dfe-002590263bf5.html