Battery stats improvements.

- Adjust total power use when there is unaccounted power so that our
  percentages don't end up > 100%.
- Fix accounting of isolated uids to be against the owning real app
  uids.
- Rework how we put cpu use into the battery stats to no longer need
  this uid name cache that can confuse the uid it is associated with.
- Finish implementing events in the history, adding a string pool and
  reading/writing/dumping them.
- Add first two events: processes starting and finishing.
- Fix alarm manager reporting of wakeup alarms to be adjusted by the
  WorkSource associated with the alarm, so they are blamed on the
  correct app.
- New "--history" dump option allows you to perform a checkin of
  only the history data.
- Fixed BitDescription bug that would cause incorrect printing of
  changes in some states.

Change-Id: Ifbdd0740132ed178033851c58f165adc0d50f716