Allow rest-client > 2.0
Allow rest-client > 2.0

The new crowbar-client needs the new rest-client version, to avoid
shipping two rest-clinet versions we just drop the ruby < 2.0 support.

SUSE-Cloud/chef,SUSE-Cloud/chef,SUSE-Cloud/chef,SUSE-Cloud/chef,SUSE-Cloud/chef,SUSE-Cloud/chef