Tweaked API layer of policy engine simulate
Tweaked API layer of policy engine simulate

Previously, if the 'delta' parameter was passed it would be
considered True, even if 'delta' was assigned the value 'False'.

This change makes the 'delta' parameter True only if it has
a value assigned and it is something we can reasonably expect
to indicate true, e.g. "True", 1, or "1".

Change-Id: I35e60eefae0f4719b720b09a23a57e2be986e272

ramineni/my_congress,ekcs/congress,openstack/congress,ramineni/my_congress,ramineni/my_congress,ramineni/my_congress,ekcs/congress,openstack/congress,ekcs/congress,ekcs/congress