Pass object to policy when finding fields to strip

During the evaluation of fields to strip in responses to list
operations, pass also the first object in the list to the
policy engine.
This will avoid errors in policy evaluation if during
an upgrade from icehouse policy.json was not updated to remove
attribute-level policies dependent on resource values.

Closes-Bug: #1323715

Change-Id: Iaa6ed3bbf4a07ce0b614a4197cabdfa1cb36d427
(cherry picked from commit 2bd97d205b98292be709b0257bda5fc489eb643a)
Merge "Pass object to policy when finding fields to strip" into stable/icehouse