network: Re-render connection title whenever it changes

The title of network connections may change if the user edits it or if
it was changed programatically by another program. This worked fine, but
the UI was not updated. This patch ensures the network list in the UI is
updated.

Reported-by: Oliver Haessler <oliver@redhat.com>

https://bugzilla.gnome.org/show_bug.cgi?id=778685