Add option to change timer alert sound

The default alert sound is sometimes quite annoying
PS1: Rebase and save the last picked value as default
PS6: WS fixes

Change-Id: I239e0d56a1562ba2c0fbff92fdf907d1147fb402
Merge branch 'cm-11.0' of git://github.com/CyanogenMod/android_packages_apps_DeskClock into cm-11.0