Fix cinder delete response which stops tempest
Fix cinder delete response which stops tempest

Change cinder delete response to pecan.response instead of a
"{}" to avoid ValueError in tempest test for cinder.

Change-Id: I5b37e7f2e23fdc0822d38e56b840e64aa87d066f
Closes-Bug: #1570306

openstack/tricircle,stackforge/tricircle,openstack/tricircle,stackforge/tricircle