message: add Catalog option Change-Id: I1aed5c4e0c278c0da697551d44fd645bc447014f Reviewed-on: https://go-review.googlesource.com/45102 Run-TryBot: Marcel van Lohuizen <mpvl@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Nigel Tao <nigeltao@golang.org>