Mailing list mode: "Upload" links broken (?) in e-mails

[zogstrip (Régis HANOL)]

@sam

If we use a straight regex gsub, this will clearly break all sorts of things for the 0.01% case but will improve the 99.9% case for the OP here.

That looks do-able and safe-ish enough.

@cvx mind adding that to your list? Before sending out an email, we need to massage the raw/markdown to change all upload:// urls into an absolute URL.