More work on device idle mode.

- There is now an API for people to find out about
  its state.
- Moved DeviceIdleController to be closer to the
  power manager implementation, since they are
  closely related.
- Job scheduler now knows about idle state and doesn't
  run jobs while the device is idle.
- Battery stats now keeps track of "idling" vs "idle mode".
  Idling is when we consider the device to be idle,
  independent of whether we are actually in deep idle mode.
  This allows us to keep track of longer-term changes
  independently of cycling in and out of idle mode.
- Battery stats also now keeps track of package changes in
  its daily stats.
- Small optimization to network policy manager service to
  not touch uids that do not have the NETWORK permission.

Change-Id: I0b3304fb3722c78cdfdd0c1eada7369ece7cbcf9