Expose :openstack_user_domain_name

[nvwls]

trafficstars

When talking to keystone v3, you need to pass in :openstack_user_domain_name. It is used, https://github.com/fog/fog-openstack/blob/master/lib/fog/openstack/auth/token/v3.rb#L103 And passing it works, albeit with a warning

[fog][WARNING] Unrecognized arguments: openstack_user_domain_name