Register a new model (models)

def post(self):
        """Register a new model (models)"""
        self.set_header("Content-Type", "application/json")
        key = uuid.uuid4().hex
        metadata = json.loads(self.request.body.decode())
        metadata["uuid"] = key
        self.database[key] = metadata
        result = json.dumps({"uuid": key})
        self.write(result)