SwaggerDeserializer does not handle RefResponse

[tschaible]

When processing paths, SwaggerDeserializer lacks handling of referenced responses and does not create objects of RefResponse type. Instead, when a referenced response is defined, an empty Response object is returned.

The simplified JSON below shows this error. It is expected that getting the response for "200" would return a RefResponse with $ref set to "#/responses/OK", however a Response is returned.

{
    "paths": {
        "/pet": {
            "get": {
                "responses": {
                    "200": {
                        "$ref": "#/responses/OK"
                    }
                }
            }
        }
    },
    "swagger": "2.0"
}