battery-device: Implement "device-added" and "device-removed"
battery-device: Implement "device-added" and "device-removed"

Implement the signal handlers for "device-added" and "device-removed"
for the battery device, so the UI can reflect adding/removal of the battery.

Patch amended by robsta@linux.intel.com

Fixes: http://bugs.meego.com/show_bug.cgi?id=2749

Signed-off-by: Gary Lin <a057d4b27e9e9055b973f54b519db54c22ed5ee8@novell.com>

meego-netbook-ux/meego-panel-devices,meego-netbook-ux/meego-panel-devices,meego-netbook-ux/meego-panel-devices