getAllEditionsActiveDuringPeriod returns incorrect list of editions

Summary

The endpoint for obtaining course editions which are active during a given period of time does not return the expected list of courses.

Steps to Reproduce

1. Use EditionControllerAPI#getAllEditionsActiveDuringPeriod to request a list of course editions active during a given period of time.
2. Receive an incomplete list of course editions.

Possible Fix

The logic for determining which courses are active contains two contradictions:

Relevant code from EditionRepository:

	default List<Edition> findAllActiveDuring(Period period) {
		return findAll((q.startDate.before(period.getStart()).and(q.endDate.after(period.getStart())))
				.or(q.startDate.after(period.getStart()).and(q.startDate.before(period.getStart())))
				.or(q.startDate.after(period.getEnd()).and(q.startDate.before(period.getEnd()))));
	}

This could be fixed and simplified as follows:

	default List<Edition> findAllActiveDuring(Period period) {
		return findAll((q.startDate.after(period.getStart()).and(q.startDate.before(period.getEnd())))
				.or(q.endDate.after(period.getStart()).and(q.endDate.before(period.getEnd()))));
	}