[2/5] packages/apps/Settings: Add dock battery support.

Dock battery patchset chain:
tf101: https://gerrit.omnirom.org/#/c/5913/
settings: https://gerrit.omnirom.org/#/c/5916/
base: https://gerrit.omnirom.org/#/c/5917/
native: https://gerrit.omnirom.org/#/c/5918/
healthd: https://gerrit.omnirom.org/#/c/5919/

Based on this patchset chain from CyanogenMod 11 by Jorge Ruesga:
Dock battery patchset chain:
base: http://review.cyanogenmod.org/#/c/55349/
native: http://review.cyanogenmod.org/#/c/55028/
healthd: http://review.cyanogenmod.org/#/c/55029/
settings: http://review.cyanogenmod.org/#/c/55212/
tf700t: http://review.cyanogenmod.org/#/c/55030/

Change-Id: I95034ef16bf3b94568d8799a11f649aebf2026b4