Sort the repos in the autoyast files

Otherwise, the file might be different each time we generate it.
Don't use by-path links for virtio disks

When using virtio disk and /dev/disk/by-id/ links don't exist for it (no serial
number configured for the disk) do not fall back to the /dev/disk/by-path
links.  These are unstable and while they are present in the discovery image,
they might not exist anymore in the deployed OS (e.g. when deploying SLES12,
which uses a more recent udev version).
Initial support for provisioning SLE12 nodes
Hard-code hostnames in each autoyast file

In SLE12, "hostname -f" doesn't return the hostname we want during
installation. It is correct later on, but not so early.

Since we use a template for each node, we can just directly hard-code
the right value in autoyast.
Do not install any package from crowbar_join

We install rubygem-chef with the autoyast profile now.

As to rubygem-ruby-shadow, it's not needed anymore as we fixed the bug
that required it to be installed early. See
https://github.com/crowbar/barclamp-pacemaker/commit/230f2a161ea220d6c1c2d51b438d1419759edbe0
make sure ssh is started
check for single or double quotes
services specification uses SLE12 syntax
Merge pull request #331 from vuntz/static-autoyast

Sort the repos in the autoyast files
Merge pull request #334 from jsuchome/adapt_for_sles12

Adaptation for SLES12
Merge pull request #332 from vuntz/sle12

Initial support for provisioning SLE12 nodes
Use correct command line options for newer sntp release on SLES 12
Merge pull request #333 from rhafer/sle-12-virtio

Don't use by-path links for virtio disks
Merge pull request #336 from rhafer/sntp-sle12

Use correct command line options for newer sntp release on SLES 12
Switch to Cloud-5 based repositories