Add a canned key

        :type key: str
        :param key: New canned key

        :type metadata: str
        :param metadata: Optional metadata

        :rtype: dict
        :return: A dictionnary containing canned key description

def add_key(self, key, metadata=""):
        """
        Add a canned key

        :type key: str
        :param key: New canned key

        :type metadata: str
        :param metadata: Optional metadata

        :rtype: dict
        :return: A dictionnary containing canned key description
        """
        data = {
            'key': key,
            'metadata': metadata
        }

        return self.post('createKey', data)