status.network wants to watch for airplane mode too, we can share the code with a manager singleton. https://bugzilla.gnome.org/show_bug.cgi?id=709128
If airplane mode is enabled with an HW switch, we can't turn it off from the menu, so make the menu item insensitive and replace it with a helpful tip. https://bugzilla.gnome.org/show_bug.cgi?id=709685
https://bugzilla.gnome.org/show_bug.cgi?id=691409
This is a simple indicator that shows if the user is currently in airplane mode, and if they are, offers a way to turn it off. It will not be shown if the user is not in airplane mode. This is a part of the new system status design, see https://wiki.gnome.org/GnomeShell/Design/Guidelines/SystemStatus/ for design details. https://bugzilla.gnome.org/show_bug.cgi?id=705845
