[COLLECTIONS-375] Added ListUtils.defaultIfNull.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1457533 13f79535-47bb-0310-9956-ffa450edef68
Remove obsolete serialization data.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1457534 13f79535-47bb-0310-9956-ffa450edef68