ciao-cli: add the ability to delete all tenant volumes

[kaccardi]

allow the user to delete all the volumes for a specified tenant.

[markdryan]

We need to check whether it's safe to provide such a command. And if it is is there a way to make the user think twice before executing it. Also, check what openstack does.

[tpepper]

At a minimum it could be a --tags debug option for dev/test.

Should be a ciao specific api, not an overloading of an openstack cinder api.