Add a canned value

        :type value: str
        :param value: New canned value

        :type metadata: str
        :param metadata: Optional metadata

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

def add_value(self, value, metadata=""):
        """
        Add a canned value

        :type value: str
        :param value: New canned value

        :type metadata: str
        :param metadata: Optional metadata

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

        return self.post('createValue', data)