Security update for grub2 (important)

Fix buffer overflows when reading username and password. bsc956631, CVE-2015-8370 - Check MS-DOS header to find PE file header. bsc954126 - Use dirname for copying Xen kernel and initrd to esp. bsc955493 - Fix reading password by grub2-mkpasswd-pbdk2 without controlling tty. bsc954519 - Add luks,...