Check attach-detach FIP & get FIP pool attributes

This patch adds the JSON schema for get Floating IPs pools
and attach & detach Floating IP APIs response and validate
the response with added JSON schema to block the backward
incompatibility change in the future.

attch, detach & delete Floating IPs does not return any
response body. So only response code is being validated.

The response body of get Floating IP pools API is below:

{
    "floating_ip_pools": [
        {
            "name": "pool1"
        }
    ]
}

Partially implements blueprint nova-api-attribute-test

Change-Id: I540b6c72fdcb6b568adbef72f5b2423a038bac7a
Merge "Check attach-detach FIP & get FIP pool attributes"