Add reporting of how jobs complete.

In both battery stats and job scheduler statistics, keep track of
the reason jobs are ending.  This can help to identify apps that
are having bad behavior with jobs (in particular, regularly timing
out their job instead of finishing it when done).

Test: manual
Change-Id: Icc12d5e0dc0df1906716e7d995c56d50a9fa148a
8 files changed