Add policy_file option to quantum.conf

Bug 1154102

Ensure /etc/quantum/policy.json is the one used by quantum when
deployed through devstack.

Change-Id: Ib4e324911d1ba631d411eb3be78355eee09c39f0
XenAPI: run DomU on a virtual kernel

Fixes bug 1154506.

Change-Id: I6e2f576a6de19db70f2a88278f9c043a433f4cec
Merge "Add policy_file option to quantum.conf"
Merge "XenAPI: run DomU on a virtual kernel"