Security updates for Thursday

CentOS has updated thunderbird (C7; C6; C5: multiple vulnerabilities).

Fedora has updated libpng (F23: two vulnerabilities).

openSUSE has updated grub2 (42.1: code execution).

Red Hat has updated kernel (RHEL6: two vulnerabilities).

Scientific Linux has updated thunderbird (multiple vulnerabilities).

Ubuntu has updated libpng (two vulnerabilities) and pygments (code execution).