Validate list_instance_usage_audit_log Nova V2 API

This patch adds the JSON schema for list_instance_usage_audit_log Nova
V2 APIs and validate the response of the API with added JSON schema
to block the backward incompatibility change in the future.

Response body of V2 List instance_usage_audit_log is below-

{
    "instance_usage_audit_logs": {
        "hosts_not_run": [
            "%(hostid)s"
        ],
        "log": {},
        "num_hosts": 1,
        "num_hosts_done": 0,
        "num_hosts_not_run": 1,
        "num_hosts_running": 0,
        "overall_status": "0 of 1 hosts done. 0 errors.",
        "period_beginning": "%(timestamp)s",
        "period_ending": "%(timestamp)s",
        "total_errors": 0,
        "total_instances": 0
    }
}

Partially implements blueprint nova-api-attribute-test

Change-Id: I9ecc3afa71b10cfbd3824bb86d02b3232c9a2594
skip test_stack_update_add_remove because of race

test_stack_update_add_remove races about 25% of the time in the
gate because the update is eventually consistent, and doesn't
happen before the list returns. It's unclear if this is
expected or unexpected behavior for heat, but 25% failure rate
is far too high.

Change-Id: I0cfd9c10c1fd5b674c1a2211f98a6aba042227da
Related-Bug: #1308682
Merge "Validate list_instance_usage_audit_log Nova V2 API"
Merge "skip test_stack_update_add_remove because of race"
Merge branch 'master' of https://github.com/openstack/tempest