This shows up when you're not running a Zephyr mirroring bot and lets
you use Webathena to have us run it. Obviously needs more docs.
Current problems include:
* supervisorctl reload ends up recreating /var/run/supervisor.sock
with the wrong permissions, so it only works once in a row before
you need to chmod that.
* /etc/supervisor/conf.d needs to be humbug-writeable; this is a clear
local root vulnerability
* This uses SSH and thus is kinda slow.
(imported from commit 7029979615ffd50b10f126ce2cf9a85a5eefd7a2)
