Added functionality for saving contacts on app close
Refactored loading reminders, saving reminders, and adding a new reminder to the Util class

The following functionality was moved to the Util class:
- Loading saved reminders
- Saving reminders
- Querying the Contacts db for a contact
Merge pull request #16 from johnschultz/14_persist_reminders_upon_closing_the_app

Fixes #14 persist reminders upon closing the app