Add a wp-content/uploads directory for noblogs

See merge request !164

This is used for media uploads for the site blog (id 1).

The config-nginx automation script requires this service to
exist (otherwise the generated NGINX config will be invalid).

add mod_announce

See merge request !163

This will be handled fully by the ai/ai-scripts automation, to
avoid conflicts due to duplicated DNS records introduced by float
and by the account-automation-frontend/templates/dns_base override.

Useful if we have to manually add ou=Operators later.

Since it runs in a container.

Per-user OpenPGP support + WKD

See merge request !161

We're storing one key per email account, along with its WKD hash
and expiration time (UNIX time).

With stricter checks on changed files.