Sign the installers

[Manu]

Hey people,

So I had a few people in the office refuse to install DMD because when
they launched the installer, Windows displayed the prompt that it was
untrusted (ie, unsigned) and not offer the install button without
manual override.
True also for VisualD.

Can we get a key and start signing the install packages?

It would be super-cool to sign the 2.081 release since it's like, imminent ;)

- Manu