Verify list-Floating-IP-Bulk Nova API attributes

This patch adds the JSON schema for Nova V2 list-Floating-IP-Bulk
API response and validate the response with added JSON schema
to block the backward incompatibility change in the future.
The response body of list-Floating-IP-Bulk V2 API is below:
{
    "floating_ip_info": [
        {
            "address": "10.10.10.1",
            "instance_uuid": null,
            "interface": "eth0",
            "pool": "nova",
            "project_id": null
        },
        {
            "address": "10.10.10.3",
            "instance_uuid": null,
            "interface": "eth0",
            "pool": "nova",
            "project_id": null
        }
    ]
}
Partially implements blueprint nova-api-attribute-test

Change-Id: I43b6f0618cb85d78577e7c63d8fbf08acc5e93a3
Merge "Verify list-Floating-IP-Bulk Nova API attributes"