Merge pull request #24 from WenhuaChang/master

propagate serial console setting to xen
new version
support grub2 on s390x
Merge pull request #25 from openSUSE/zipl

support grub2 on s390x
update changes and version
snapper rollback support

Add handling of SUSE_BTRFS_SNAPSHOT_BOOTING in /etc/default/grub and
calling suse_btrfs_grub2_install.sh if that settings is enabled and both
/boot and root are on btrfs file system. (fate#317062)