Verify attributes through Nova list flavor-access API

This patch adds the JSON schema for Nova V2/V3 list flavor-access APIs
includes the attributes to block the backward incompatibility change
in the future.

The response body of v2 and v3 API is the below:
{
    "flavor_access": [
        {
            "flavor_id": "10"
            "tenant_id": "231a1e7fd1b344f9874d0334d98b459c"
        }
    ]
}

In addition, this patch doesn't change V3 test because it is skipped
owing to the bug.

Partially implements blueprint nova-api-attribute-test

Change-Id: I027dc96e5702cd03a7b85ba41c4c30215e321f30
don't log cli output on success

we only should log cli output on failure, not success. So just
leave it to the exception to log it. This helps reduce the needless
spam inside the tempest log.

Change-Id: I1623694d7321e679e8438eba3e6b1ad58fc6e855
Merge "don't log cli output on success"
Merge "Verify attributes through Nova list flavor-access API"
Merge branch 'master' of https://github.com/openstack/tempest