OAK-1081 - Node.getNodes throwing exception if user does not have access to any child node

Node.getNodes() would now filter out nodes to which the session does not have access to.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1530552 13f79535-47bb-0310-9956-ffa450edef68