Installing Fedora on a bunch of machines, simultaneously or in rapid
succession, can be painfully slow, as several large files need to be
downloaded. To speed this up, we download those files via the proxy and
cache them on the proxy server.
As a side-effect, the proxy needs to allow access to the Kickstart
"server" (i.e. my workstation, at least for now), since Anaconda will
use the configured proxy for everything it downloads.