Make nova compute deployable on SLE12

  We want to adopt barclamp-nova and
  make it deployable on SLES12 nodes.
  We have to fix followings parts
  in nova cookbook:
    - grub configuration
    - iscsid service name
    - skip boot.multipathd service
    - editing /etc/libvirt/qemu.conf
Silence deprecation warnings with newer ruby releases (SLE12)
Use real logging calls instead of puts
Use templates for /etc/libvirt/qemu.conf

Using sed/grep for updating qemu.conf turned out to be error prone. see
discussion in: https://github.com/crowbar/barclamp-nova/pull/400/

Note instead of putting the SLE12 specific template into templates/suse-12.0
this is using a different template name inside the default directory to avoid
having to have additional templates for future service packs of SLE12 (SP1
would require using templates/suse-12.1).
Fix grub2 config update code

The grub.cfg "menuentry" lines for Xen on SLES12 contain whitespaces.  Use a
regexp for extracting the name instead of split().
Merge pull request #412 from rhafer/sle12-compute

Make nova compute deployable on SLE12