Settings: Add Advanced reboot (1 of 2)

This commit adds a setting in Development settings for including options
in the power menu for rebooting into recovery or bootloader, defauled to
off.

When enabled, the Advanced reboot options will only be available once the
device is unlocked.

Change-Id: Ib77f0be178d15131b99adbe0abb6ba18b2b7c0b6