notifications_view: Check for notification image before app image

The spec states that the image data from a notification should be used before the application icon or any other icon. This change should reflect that.

It seems to fix #477. Nemo and Twitch Streamlink notifications now display properly in Raven on my system.

Signed-off-by: Evan Maddock <maddock.evan@vivaldi.net>

src/raven/notifications_group.vala

@@ -87,7 +87,7 @@ namespace Budgie {
 		public NotificationGroup(Budgie.Notification notification, NotificationSort sort_mode, uint keep) {
 			Object(
 				app_name: notification.app_name,
-				image: notification.app_image ?? notification.image ?? new Gtk.Image.from_icon_name("applications-internet", Gtk.IconSize.DND),
+				image: notification.image ?? notification.app_image ?? new Gtk.Image.from_icon_name("applications-internet", Gtk.IconSize.DND),
 				tokeep: keep,
 				noti_sort_mode: sort_mode,
 				activatable: false,