Framework: Add Advanced reboot (2 of 2) By DvTonder

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

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

Change-Id: I675f31de1f82c344c7923e953fd4a6e26dd036da

Conflicts:
	core/res/res/values/custom_strings.xml