Power manager now prevents wake locks from idle uids.

The activity manager now pushes the idle/active state
down in to the power manager.  The power manager now
tracks a structure of data about each uid: how many
wake locks it holds, whether it is active, and (as before)
its current process state.

Now when apps are inactive, we always disable wake locks
they hold, regardless of the system's device idle or
other state.

Test: none

Change-Id: I2cd4077e4d8a8572525406ae9747f0a2435764da