Don't copy certificates for 802-1x connections to our own storage.

I've thought a lot about this, and while this was a very cool feature
for NM 0.8, where we had our own little connection list that only we
could access, this doesn't fit into NM 0.9 anymore. As soon as the
connection gets modified/deleted by something other than ourselves, be
it nm-applet or the sysadmin editing the files in
/etc/NetworkManager/system-connections by hand, we get problems, like
deleted/missing certificates or obsolete certificates still floating
around.

Everything still works, tested with WPA2-EAP-PEAP and WPA2-EAP-TTLS
(eduroam)