Currently, if firewalld is not running, then the firewall zone combo is
always insensitive. This would make sense if firewalld was great and we
were to consider it a distro bug to not have firewalld running and
enabled, then users would be able to see the option is disabled and
think "maybe my distro has done something wrong."
But in actuality, firewalld is not really great, only Fedora ships it
and we're not really recommending it to other distros. So hide the combo
if it's not running, else it's just broken on $NOTFEDORA.
https://bugzilla.gnome.org/show_bug.cgi?id=763477
This code is fairly independent of the rest, and we don't want
net-device-wifi.c to become too massive and unmaintainable.
The code in connection-editor/ is fairly similar to
nm-connection-editor, with some simplification because we
currently only edit wireless connections.
The code in wireless-security/ is almost a straight copy
of the same code in nm-connection-editor, with some changes
to the .ui files to make them fit better in the new design.
