Bumping to HTML5 & adding device friendly meta tag

Because why not :)

...so one doesn't need to mess around with setcap.

We will be using an HTTPS-enabled reverse proxy for this service, so we
only need to talk HTTP.

The http package can log error messages that include the client's IP
address.  We don't want any IP addresses in our log file and snowflake's
safe logger can scrub them.

Thanks to Cecylia for suggesting this here:
<https://bugs.torproject.org/30472#comment:6>

Thanks to Cecylia for suggesting this here:
<https://bugs.torproject.org/30472#comment:6>