Settings: make unaccounted and over-counted battery usage configurable

Google disabled it for release builds here:

https://github.com/SlimRoms/packages_apps_Settings/commit/e6793771cedb47aed72f1c64f870b70357746938

well but it is enabled for whatever other type of builds beside the official release builds. That said it should
be a developer option so or so and not build type dependent.

Whatever added an option into developer settings to control it. Default value is false.

That said.....finally no complain about misc battery stat in battery settings xD

Change-Id: I7549b1c796d5d9413b4af5d80a31d6efeaf0352a