Roles action uc_roles_action_user_email() uses non-existent $order

This looks like a bit of bad copypasta... the function references an $order variable like it's sending an e-mail for an order, but the purpose of the action is to send an e-mail using just a user account and role expiration - i.e. it's order agnostic. Nothing fails, but it should be cleaned up so the error message is meaningful and order tokens aren't expected.