cLock: Updates to how dates are displayed in calendar entries

This commit:
- Removes the display of the date in calendar entries when the
  interval is below one week
- Switches formatting of date in calendar entries from manual
  localized formatting strings to DateUtils locale-aware format methods
- Adds full date if events are > 1 week

Screenshots:
- Before:
  https://dl.dropbox.com/u/39911341/screenshot_confusing_appointments.png
- After:
  https://dl.dropbox.com/u/39911341/screenshot_confusing_appointments_fixed.png

Change-Id: I29883fc9c81229d4fd25a74428a997eef1c27c62