webadmin: Allow default profile to turn into ghost entry

Previously this was blocked, seemingly because generally ghost
toggling events weren't being triggered for the default profile (when
it was being update via the network name). This is hopefully fixed by
registering for the model event itself.

Change-Id: I0330a07a4af5b911aaa5c3214d56ae381771c0cc
Bug-Url: https://bugzilla.redhat.com/1064396
Signed-off-by: Lior Vernia <lvernia@redhat.com>