Add the 308 Permanent Redirect status code

src/cow_http.erl

@@ -298,6 +298,7 @@ status(304) -> <<"304 Not Modified">>;
 status(305) -> <<"305 Use Proxy">>;
 status(306) -> <<"306 Switch Proxy">>;
 status(307) -> <<"307 Temporary Redirect">>;
+status(308) -> <<"308 Permanent Redirect">>;
 status(400) -> <<"400 Bad Request">>;
 status(401) -> <<"401 Unauthorized">>;
 status(402) -> <<"402 Payment Required">>;