missing snapshots related value in used_limits API

[Liyingjun]

when calling the limits we can only get {"maxTotalVolumeGigabytes": 1000, "totalGigabytesUsed": 2, "totalVolumesUsed": 1, "maxTotalVolumes": 10}, snapshots related limits data is missing.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/75337

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/75337
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=c9c6befe7e19adc168aefe1cfaeac8d68dd398fa
Submitter: Jenkins
Branch: master

commit c9c6befe7e19adc168aefe1cfaeac8d68dd398fa
Author: liyingjun <email address hidden>
Date: Fri Feb 21 02:58:58 2014 +0800

    Add snapshot related data to limits api

    When calling the limits api we can only get Volume and Gigabyte data,
    the snapshot related limit value should be returned too.

    Change-Id: I6a5e1e2d1aa6abbac5d5dacd042223ce49207c1f
    Closes-bug: 1282924