NetworkMenu: show the device name instead of Bluetooth

To distinguish the bluetooth network menu from the bluetooth
menu proper, use the device name as the label.
Also, replace Connect with "Use as Internet connection"

https://bugzilla.gnome.org/show_bug.cgi?id=709353
BluetoothMenu: show the submenu when active but not connected

Following the updated designs for system status, show the submenu
but not the indicator when bluetooth radio is on but no device
is connected.

https://bugzilla.gnome.org/show_bug.cgi?id=709353