Add Switchpreference for Lockscreen Blur

Now it goes well with the LSN & Peek Switches...
[2/2] Settings: Add an option to reset custom user preferences

Change-Id: I07223fe924860dee0ce22d0946d569eeef6b9d7e

Conflicts:
	res/values-es/pa_strings.xml
	res/values/pa_strings.xml