Add a response schema for "log" attribute

During the nova reivew of Ic1a307c405f769cadd037ae45e921d88b6a2bea5 ,
we found the lack of the response schema for "log" attribute.
The "log" attribute should have state, instances, errors and message
according to https://github.com/openstack/nova/blob/master/nova/api/openstack/compute/instance_usage_audit_log.py#L104

Then this patch adds them to the response schema.

Change-Id: I1c0fab7ba54cc346e9f9f2308c8a46f5ee00b9d6
1 file changed