This patch is a refactor of the prototype sys condition plugin. It
moves most of the logic to monitor kernel events into a keventd that,
currently only, sets and clears the sys/pwr/ac condition. The sys
plugin itself is now only a monitor of conditions and ensures Finit
follows them. This is a lot more secure and moves (at least one piece
of) netlink processing out from PID 1.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>