Settings: Advanced low battery indicator options (2/2)

Based on a Slim Roms implementation with a special thanks to @kufikugel
This commit introduces following new modes to indicate low battery.
Accessible through action bar following new PA way of custom features (clean and simple)
     * 0 = show dialog + play sound (default)
     * 1 = fire notification + play sound
     * 2 = show dialog only
     * 3 = fire notification only
     * 4 = play sound only
     * 5 = none

Change-Id: I2d5358962c3bbf7b60c8af19aad9db3a4a8071de