Settings: Custom lock screen background [2/2]

Patch Set 1:    * port the custom lock screen feature from
                  ics (http://review.cyanogenmod.org/#/c/16914)

Patch Set 2:    * rename some strings
                * use constants instead of numbers
                * fix some code styling issues

Patch Set 3:    * code cleanup

Patch Set 4:    * rebased

Patch Set 5-6:  * code cleanup

Patch Set 7:    * fix comment location

Change-Id: I35e5c70fff423770a03b5bb39d439ebea82dd56a

Conflicts:
	res/values/arrays.xml
	res/values/strings.xml
	src/com/android/settings/carbon/LockscreenInterface.java
fix fc if the navbar icon is null

Patch Set 2: Added an icon to return if the old one is null

Change-Id: I4ff60e6da624f482518fb065227bd356dd97d5f1
Merge branch 'jb2' of git://github.com/CarbonDev/android_packages_apps_Settings into jb2