Bump version number

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1578989 13f79535-47bb-0310-9956-ffa450edef68
Document release of 3.3.1

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1578990 13f79535-47bb-0310-9956-ffa450edef68