Add missing version/since tags, throws clauses.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1459551 13f79535-47bb-0310-9956-ffa450edef68
Formatting und removal of unused import.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1459552 13f79535-47bb-0310-9956-ffa450edef68