Maybe fix issue #2457218: Corrupt batterystats.bin file preventing phone boot - LIBtt68127

No steps to repro, but makes the code more robust by using the standard
JournaledFile class and doing sanity checks on the input it reads.

This required moving the JournaledFile class in to the framework (and
we really should get rid of either it or AtomicFile, but they have
different recovery semantics so that is tough).  Also went through and
cleaned up the file management in various places.

Change-Id: Ieb7268d8435e77dff66b6e67bb63b62e5dea572e