#13259 - Hammer : add addtional volume to Openstack via l'api Hammer

Similar to Feature #11577 <Feature #11577: Add additional volume to OpenStack - Foreman>,
when creating a new vm using Openstack with Hammer API, additional volumes
won't be created. I have implemented and tested this feature in our
development environment.

I put only volume attributes.

hammer :

Will push the code to github afterwords.