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
Use actual storage type for format message strings

Change-Id: I214120303bf6c12c297332fa314ce80bc686da46