Verify detail_list flavor attributes of V2/V3 APIs

This patch adds the JSON schema for Nova V2/V3 detail_list flavor APIs
response and validate the response with added JSON schema to
block the backward incompatibility change in the future.

The response body of V2 detail_list flavor API is below:

{
    "flavors": [
        {
            "name": "m1.tiny",
            "links": [
                {
                    "href": "http://openstack.example.com/
                             v2/openstack/flavors/1",
                    "rel": "self"
                },
                {
                    "href": "http://openstack.example.com/
                            openstack/flavors/1",
                    "rel": "bookmark"
                }
            ],
            "ram": 512,
            "vcpus": 1,
            "swap": "",
            "disk": 1,
            "id": "1",
            "OS-FLV-DISABLED:disabled": false,
            "os-flavor-access:is_public": true,
            "rxtx_factor": 1.0,
            "OS-FLV-EXT-DATA:ephemeral": 0
        }
    ]
}

The response body of V3 detail_list flavor API is below:

{
    "flavors": [
        {
            "name": "m1.tiny",
            "links": [
                {
                    "href": "http://openstack.example.com/
                             v3/openstack/flavors/1",
                    "rel": "self"
                },
                {
                    "href": "http://openstack.example.com/
                            openstack/flavors/1",
                    "rel": "bookmark"
                }
            ],
            "ram": 512,
            "vcpus": 1,
            "swap": 0,
            "disk": 1,
            "id": "1",
            "disabled": false,
            "ephemeral": 0,
            "flavor-access:is_public": true,
            "os-flavor-rxtx:rxtx_factor": 1.0
        }
    ]
}

Partially implements blueprint nova-api-attribute-test

Change-Id: I3a07ada712271d0d147c0019bbb4b63c4622461a
Merge "Verify detail_list flavor attributes of V2/V3 APIs"