Javadoc fix.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1559745 13f79535-47bb-0310-9956-ffa450edef68
IntervalsSet now implements Iterable<double[]>.

Fixes MATH-1090

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1559746 13f79535-47bb-0310-9956-ffa450edef68