Document the recent remote site takeover via SQL injection vuln in Joomla

While here, document all missing Joomla security vulnerabilities since the
last entry in March 2014

Security: CVE-2014-6631
Security: CVE-2014-6632
Security: CVE-2014-7228
Security: CVE-2014-7229
Security: CVE-2015-5397
Security: CVE-2015-5608
Security: CVE-2015-6939
Security: CVE-2015-7297
Security: CVE-2015-7857
Security: CVE-2015-7858
Security: CVE-2015-7859
Security: CVE-2015-7899
Security: https://vuxml.FreeBSD.org/freebsd/0ebc6e78-7ac6-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/03e54e42-7ac6-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/f8c37915-7ac5-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/ec2d1cfd-7ac5-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/deaba148-7ac5-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/cec4d01a-7ac5-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/beb3d5fc-7ac5-11e5-b35a-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/adbb32d9-7ac5-11e5-b35a-002590263bf5.html