Chapter 23: Initial commit.
SOLVED CHAPTER 21 GOLD CHALLENGE!

The Apple-recommended method didn't work:
[self.tableView registerClass:[KLBUpcomingCoursesCell class] forCellReuseIdentifier:@"KLBUpcomingCoursesCell"];

But this did:
UINib *nib = [UINib nibWithNibName:@"KLBUpcomingCoursesCell" bundle:nil];
[self.tableView registerNib:nib forCellReuseIdentifier:@"KLBUpcomingCoursesCell"];