Setup security@archlinux.org mailing list for the Security Team

The security team wants to offer a way to report security issues related to arch securely using PGP encrypted mails. This uses a publicly known PGP key for the security@archlinux.org email address and forwards the email by re-encrypting it to the security team.

Schleuder is a piece of software which offers this functionality, it is to be packaged in the repos to be used in our infrastructure.

Since this requires a private key on our server, we should consider using a new server or a server with limited access.

Migrated from: https://kanboard.archlinux.org/project/1/task/98