Status bar: Add brightness control, (1/2):

Thanks to OmniRom:
https://github.com/omnirom/android_frameworks_base/commit/62596e0e6282ba625042ba39e9daae5e2088199c
https://github.com/omnirom/android_frameworks_base/commit/3fde98623d16a63d2575efe7bb78b406065b59e2