hyperv: handle license_key=nil
Install rubygem-ruby-shadow during crowbar_join --setup for SUSE

This is needed when we want to change user passwords.
Merge pull request #280 from SUSE-Cloud/release/roxy/master

hyperv: handle license_key=nil
Merge pull request #281 from vuntz/ruby-shadow

Install rubygem-ruby-shadow during crowbar_join --setup for SUSE