Fix error with invalid default uris

An invalid default uri resulted in an infinite loop:
alarm.alert is invalid -> set to default uri -> invalid again -> set again

Also the default alarm was removed, so using that is not an option

Change-Id: Ibc3cee6dd440b1dd8d260b27101595509f5155b1
Merge branch 'cm-11.0' of git://github.com/CyanogenMod/android_packages_apps_DeskClock into cm-11.0