tenant should be able to get volume_tenant_attribute default

[Liyingjun]

Currently, volume_extension:volume_tenant_attribute in policy.json is set to rule:admin_api default, i think the volume_tenant_attribute should be access for tenant own by default.
There will be a issue for horizon, If we using the default policy.json file for cinder, see exactly https://bugs.launchpad.net/horizon/+bug/1269304

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/66792

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/66792
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=13f0468e376a17ea7811b97c5a8f72bb63d52249
Submitter: Jenkins
Branch: master

commit 13f0468e376a17ea7811b97c5a8f72bb63d52249
Author: liyingjun <email address hidden>
Date: Sun Jan 12 23:19:44 2014 +0800

    Change default policy for volume_extension:volume_tenant_attribute

    The volume_tenant_attribute extension should be accessible by
    the owning tenant and the admin. Change default policy from
    'rule:admin_api' to 'rule:admin_or_owner'.

    Change-Id: I886cd717741c86b5083aeaf16e3e7ea5b4e525b4
    Closes-bug: #1269312