Improve screen timeout QS tile

 * Use com.android.internal.R.plurals.duration_* for text
 * Use white icon as suggested here https://jira.cyanogenmod.org/browse/CYAN-3769

Change-Id: Idfedbc1e7a857dbfa05736810e09528852c8bfa3

Conflicts:

	packages/SystemUI/src/com/android/systemui/quicksettings/ScreenTimeoutTile.java