Add policy for builtin message sources

Some notifications, despite being emitted by shell code, should appear
to be from application or "separable" system components. Do that by
associating them with a notification-daemon policy.

Note that for this to look really good, empathy should rename itself
to Chat.

https://bugzilla.gnome.org/show_bug.cgi?id=685926

js/ui/status/network.js

@@ -20,6 +20,7 @@ const Main = imports.ui.main;
 const PanelMenu = imports.ui.panelMenu;
 const PopupMenu = imports.ui.popupMenu;
 const MessageTray = imports.ui.messageTray;
+const NotificationDaemon = imports.ui.notificationDaemon;
 const ModemManager = imports.misc.modemManager;
 const Util = imports.misc.util;
 
@@ -1783,6 +1784,7 @@ const NMApplet = new Lang.Class({
         if (!this._source) {
             this._source = new MessageTray.Source(_("Network Manager"),
                                                   'network-transmit-receive');
+            this._source.policy = new NotificationDaemon.NotificationApplicationPolicy('gnome-network-panel');
 
             this._source.connect('destroy', Lang.bind(this, function() {
                 this._source = null;