Add deviation to favourites

        :param deviationid: Id of the Deviation to favourite
        :param folderid: Optional UUID of the Collection folder to add the favourite into

def fave(self, deviationid, folderid=""):

        """Add deviation to favourites

        :param deviationid: Id of the Deviation to favourite
        :param folderid: Optional UUID of the Collection folder to add the favourite into
        """

        if self.standard_grant_type is not "authorization_code":
            raise DeviantartError("Authentication through Authorization Code (Grant Type) is required in order to connect to this endpoint.")

        post_data = {}

        post_data['deviationid'] = deviationid

        if folderid:
            post_data['folderid'] = folderid

        response = self._req('/collections/fave', post_data = post_data)

        return response