The CoursesController learned a 'cutoff' argument for course listings.

The default is still 4 years, but now ISO-8601 Durations can be specified
as a 'cutoff' parameter. This will allow selectable periods of less than 4
years.

See:	https://en.wikipedia.org/wiki/ISO_8601#Durations
	http://php.net/manual/en/class.dateinterval.php