Signed release tags

[Joel Brobecker]

> > IMHO it would be nice to have the release tag in git be GPG-signed.
> > WDYT?
[...]
> Anyways, no objection from me. I'll just follow whatever people
> think is best.

There was no other reaction to this suggestion, but it was easy to do,
and I do not see how this could possibly hurt, so I went ahead and
implemented it. The 7.1.1 release tag, and all future tags should now
be signed.

-- 
Joel