install-chef-suse: Remove handling of SP1 and SP2 repos

With SP3, we don't require any previous service pack.
install-chef-suse: Add scary message if running this on deployed admin

Once /opt/dell/crowbar_framework/.crowbar-installed-ok exists, then the
installation went to completion, and we don't want people to run this
again unless they know what they do.
Merge pull request #1822 from vuntz/install-chef-suse

+1