Show remaining time on countdown notification

[OldSneerJaw]

Currently the countdown notification shows the absolute date and time that the timer is set to expire; instead, periodically (e.g. every minute) update the notification's text with the number of hours and minutes remaining.

A service can be run in the foreground with an associated notification to accomplish the desired effect: http://developer.android.com/guide/components/services.html#Foreground