Changed ListDelimiterHandler.parse() to return an Iterable.

Changed return type from Iterator to Iterable. This is more flexible. The
NodeModel interface expects an Iterable to be passed in.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/branches/immutableNodes@1573217 13f79535-47bb-0310-9956-ffa450edef68