Add response schema for V2 sec grp default rule

This patch adds response schema for nova V2
'os-security-group-default-rules' APIs.

Response body of create/show 'os-security-group-default-rules' -
{
    "security_group_default_rule": {
        "from_port": 80,
        "id": 1,
        "ip_protocol": "TCP",
        "ip_range":{
            "cidr": "10.10.10.0/24"
        },
        "to_port": 80
    }
}

Response body of list 'os-security-group-default-rules' -
{
    "security_group_default_rules": [
        {
            "from_port": 80,
            "id": 1,
            "ip_protocol": "TCP",
            "ip_range": {
                "cidr": "10.10.10.0/24"
            },
            "to_port": 80
        }
    ]
}

Delete API only returns 204 status code.

Change-Id: Id24857ee95445570d45aac3e1a25e607d8df78d1
Merge "Add response schema for V2 sec grp default rule"