batteryservice: add battery current now and charge counter data

Available for retrieval via future APIs if desired.  Dumped by dumpsys.
Not added to batterystats or ACTION_BATTERY_CHANGED intents at this point.

Also fixes a formatting problem in the existing dumpsys output for voltage.

Change-Id: I5320b19035914256fb872c13095c09c648dd522a
2 files changed