Currently we can get instance usage audit logs via Nova API,
and the docs also update for it. It is necessary to add that
to our client and CLI.
This patch adds the following command.
nova instance-usage-audit-log [--before <before>]
Co-Authored-by: Takashi Natsume <natsume.takashi@lab.ntt.co.jp>
Change-Id: I4ef8e40c322f1768ee1b5e01e9681cab0e2804bd