Heading For Tight Quarters - The first family into a local low-rent housing project is a whopper. Heading for their seven-room apartment are John and Helen Washington and their 15 kids.From left are pop; Leo, 3; Edward, 4; Frank, 5;Michael, 6; Betty, 7; Richard, 9; Thomas, 10; Margaret, 11; Mary, 12; James, 13; Ellen, 14; Eugene, l5; Bernard, 16; John, 17; and mom, carrying Kathleen, one year old. The father, a $4,200 a year bus driver, plans two double-decker bunks in each of four bedrooms for