Decommission vsw.probcomp.sinens.is and associated resources

[axch]

• (Decommission vsw.probcomp.sinens.is and associated resources #22 (comment)) Shut down EC2 instance.
• (2017-06-30) Remove vsw.probcomp.sinens.is DNS records.
• Wait for 2-day DNSSEC signature to expire on 2017-07-02.
• Release elastic IP address.
• Delete remaining resources.

[axch]

Coordinated with Veronica. She doesn't need anything linked to this machine; we are clear to decommission all resources associated with vsw.probcomp.sinens.is.

Renaming the ticket accordingly.

[axch]

(I stopped the instance, so we are not bleeding money while this cleanup happens.)