Various updates, generally overdue or MIT firewall related

Various updates, generally overdue or MIT firewall related

- bots: Google Hangouts is dead, so don't check for the Hangouts-related bots
- Migrate DNS from chankillo to goslar (for the MIT firewall,
  adehnert-sysconfig/salt #64)
- Check that proxy1 is serving mail services (again for the MIT firewall)
    - It also forwards the KDC, but we don't have an existing check for it, and
      it seems unlikely that mail would work but KDC forwarding would go down,
      without an issue with masada, which has its own (ping) monitoring
- olinda has been dead for ages; just delete the file -- we can restore it from
  git if needed