Light settings: reduce tone if preview image color is very light

Prevents material whiteout in color preview.

Change-Id: Idfa47e57bdb669b17b610b737d0fe2c942b47d78
Development Settings: fix setting reset on disable

When Development Settings are disabled, some settings are
reset to values other than the default. This fixes it.

 - Adb notify should reset to enabled

 - Verify apps over usb should reset to enabled

Change-Id: Ifa1ee25cfab32b7a236e02055006f0d2a4b07f37