[openpgp] SHA-2 support should be mandatory – change defaults

[Heinz Diehl]

On 13.08.2014, Johan Wevers wrote: 

> Most people, inclusing me, have stopped using it. However, I still have
> a lot of mail archives from those days. Removing support would mean I
> have to start using pgp 2 again to access them.

Or the most recent version of gnupg with support for those mail
archives..