Some additional pieces to bring install-chef-suse.sh back into shape

This pull requests adds:
"bc-dns-json.rb" to add the forwarder defined in resolv.conf to the dns template
and
"bc-network-admin-helper.rb" to sanity-check if the IP of the admin host is actually inside the admin network's range.
Both tools are called by install-chef-suse.sh

This also adds some fixes to the $CROWBAR_TESTING mode of install-chef-suse.sh, which is supposed to do a crowbar admin nodes installation with installing the barclamps from git checkouts instead of packages.