Settings: Add Advanced reboot option
By DvTonder

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: I692fb732ec1b14ae9a71f2de4b343a05934cdcf9

Conflicts:
	res/values/custom_strings.xml
[1/2] settings: Set AdvancedReboot to be enabled by default
RE: http://jira.omnirom.org/browse/OMNI-1

Fixing as I am a stupid head

Edit 9001: Setting this to be enabled by default for all users

Change-Id: I08a0e0cbe821e4d2dad6cf2a9ac20721cd19d69b
[2/2] Settings: enable advanced reboot by default only if developer options are enabled

Change-Id: I0b074cd3b6f2fd8515e917cf4a8a65639d6be2e4
fixes & power menu options backport