* AlarmManager-based notifications, with user-defined notification
times, function.
* Notifications _should_ run automatically on device boot-up. (Not yet
tested.)
* Still need to flesh-out the logic for each notification time & type.
* Bugfix: NewFocusBoardActivity removes itself from the activity stack,
such that creating a new mantra board, then hitting the Back button,
properly returns the user to the home activity, rather than the
mantra-board-creation activity.