Support for sleep in HEAD

[Dan Williams <dcbw redhat com>]

Hi,

I've added two dbus calls on the /org/freedesktop/NetworkManager object:

sleep - deactivate and set all devices down
wake  - wake up and go through device activation

These should help out with David's work with HAL and power management.  It could 
use some testing to make sure that NM doesn't hold any references to devices 
when its supposed to be asleep.

Dan