Settings: QS performance profiles tile

Requires http://review.cyanogenmod.org/#/c/51776/

Patchset 2: Fix not null comparation
Patchset 3: Added suggestions
Patchset 4: Fix string
Patchset 5: Rebased
Patchset 6: Rebased
            Move setCurrentValue() inside mPerfProfilePref null check

Conflicts:
	res/values-cs/cm_strings.xml
	res/values-de/cm_strings.xml
	res/values-el/cm_strings.xml
	res/values-es/cm_strings.xml
	res/values-hu/cm_strings.xml
	res/values-it/cm_strings.xml
	res/values-pt/cm_strings.xml
	res/values-ru/cm_strings.xml
	res/values-sk/cm_strings.xml
	res/values-zh-rTW/cm_strings.xml
	res/values/cm_arrays.xml
	res/values/cm_strings.xml
	res/xml/perf_profile_settings.xml
	src/com/android/settings/cyanogenmod/PerformanceSettings.java

Change-Id: I578d84002b00e0a7c58cdcaf2a3735bf6bbfdabf
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>