Fix #306: ignore http_error tuples in yaws_api:fold_others/4

When processing HTTP headers in yaws_api:fold_others/4, ignore
http_error tuples and other values that are not http_header tuples.

src/yaws_api.erl

@@ -1505,7 +1505,9 @@ fold_others(LowerHdr, Handler, Other, StartAcc) ->
                                       is_binary(Hdr) -> binary_to_list(Hdr);
                                       true -> Hdr
                                   end),
-                        Handler(HdrVal, HdrNm == LowerHdr, Acc)
+                        Handler(HdrVal, HdrNm == LowerHdr, Acc);
+		   (_, Acc) ->
+			Acc
                 end, StartAcc, Other).
 
 erlang_header_name("cache-control")       -> 'Cache-Control';