Can use volume_id in nova.volume.cinder.API to reduce roundtrips with Cinder

[Oleg Bondarev]

Currently volume.cinder.API methods accept volume object as a parameter while the majority of them only needs volume_id.
So API users need to do a redundant roundtrip with Cinder: first to get volume object and then pass it to another method (which only needs volume_id).
For example:
nova.api.openstack.compute.contrib.volumes.VolumeController.delete():
 ...
        try:
            vol = self.volume_api.get(context, id)
            self.volume_api.delete(context, vol)
 ...

while volume_api.delete() method is just:
    def delete(self, context, volume):
        cinderclient(context).volumes.delete(volume['id'])

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/27537

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/27537
Committed: http://github.com/openstack/nova/commit/586e752e69ca891714f390bf59ad30d5081d4498
Submitter: Jenkins
Branch: master

commit 586e752e69ca891714f390bf59ad30d5081d4498
Author: Oleg Bondarev <email address hidden>
Date: Fri Apr 26 12:52:26 2013 +0400

    Refactor nova.volume.cinder.API to reduce roundtrips with Cinder

    Make cinder.API methods accept volume_id instead of the whole volume object.
    This will remove redundant roundtrip to get the volume before
    passing it to other methods as in fact they only need the id.

    Fixes bug 1172297

    Change-Id: I5e7f944c1c29b2f211ece2ef86c0959c81e806df