Add default to metadata in 99-refresh-completed

This metadata isn't present on the seed, causing the calls to
os-apply-config to fail.

Change-Id: Ia2978599013ccd3f39a06e0d8163b62a887c1f6e
Use upstream nova policy.json

We were using a local copy that was out of date and causing at least two
tempest tests to fail, specifically the tests that lock/unlock instances
as we were requiring admin privileges in our policy.json.

Change-Id: I73c64607d92563b10464aa2d31de2305b63b91e4
Merge "Use upstream nova policy.json"