Volume attach task in openstack-create should be validated

[vvaldez]

While using a new OpenStack environment with ose-provison.yml I had some Cinder issues. Due to this the volume attach task didn't report an error but also did not attach to the instance. Therefore the docker storage task later in the playbook fails as there was no additional volume attached to the instances.

I propose we add a task after the volume attach to validate it is successful in roles/openstack-create/tasks/create-volume.yml. Currently the final task in this play calls nova volume-attach which is an asynchronous command so the command succeeds if it schedules the action but does not guarantee that the action was successful. A task after this should be added to wait until nova volume-list shows it attached to the instance.