Get the difference of two dates in minutes
minuteDiff(new Date('2012-12-21 00:00:00'), new Date('2012-12-21 00:30:00'));
// 30
minuteDiff(new Date('2012-12-21 00:00:00'), new Date('2012-12-21 00:00:30'));
// 0.5
minuteDiff(new Date('2012-12-21 00:00:00'));
// However many minutes from doomsday to now