Firewalld is a Fedora-only daemon, and it doesn't integrate all that
well with Fedora Workstation, the version of Fedora that uses GNOME, so
remove the support.
In Fedora Workstation, firewalld only ever supports one zone, as the
other ones are badly defined, and not translatable or translated.
Unfortunately, the VPN plugins provide their own .ui files for their
editor pages, so we can't make them look competely GNOME-3-ish. But
the code does try to fix them up a little bit by realigning the
labels.
vpn-helpers.[ch] is nearly identical to network-manager-applet's,
but eventually this code will move into libnm-gtk.
https://bugzilla.gnome.org/show_bug.cgi?id=691285
