We just need the target platform version in the template

Rework the version check to be on the safe side for a future SP4 update for
SLES 11.
Use systemctl on SLES12 to enable chef-client
SLES12 uses a different mechanism to enable/diable core dumps
Set hostname in autoyast network config

This seems to be needed on SLES12, otherwise the hostname is not configured
correctly when crowbar_join.sh is running.
Merge pull request #338 from rhafer/sle12

adjustments to get crowbar_join.sh SLES12 succeeding
Bugfix: hostname: Host name lookup failure

Bug: https://bugzilla.novell.com/show_bug.cgi?id=886238

Fixed the bug: If the /etc/resolv.conf is broken, "hostname -f" could not say
the hostname of the current host.

Resolution: Added a new entry in the /etc/hosts file. (IP, FQDN & Hostname)