TapQueue server and station 0.11.0

Added

• Backups. The server backs up its database, TLS certificate and Active Directory CA into
  data_dir/backups every day at 02:00 (the newest 7 are kept) and before an upgrade changes the
  database. tapqueue-admin backups and Server → Backups in the console list them, make one
  now, download and delete them and change the schedule; full admins only, since a backup holds
  every hashed password and the server's private key. Restore one with the server stopped:
  sudo -u tapqueue /opt/tapqueue/tapqueue-server --restore <file>, which moves what was there
  aside instead of deleting it. Held documents and published builds aren't in a backup, and the
  backups are on the server's own disk: copy them off with tapqueue-admin backups download latest.
  See docs/backup.md.