Stubout cinder.tenant_absolute_limits in cinder test

To render dropdown actions to detail page, allowed() method
in the volume table is called, so a method called in allowed()
needs to be stubout.

Change-Id: Ib65eee0fa2c8b6535e1e391579fcd1bdb0f83bc1
Closes-Bug: #1378907
Merge "Stubout cinder.tenant_absolute_limits in cinder test"