Cleanup of lock screen widget code:

- Don't duplicate stringToLongArray function, put it in Settings class
  instead
- Remove unused argument from vibrate() function
- Don't hardcode time format strings, use DateFormat class instead
- Also use DateFormat class to retrieve 12/24 hour selection value

Change-Id: Idda45d97df0e966a1a9e208f9730284ed0268088