OAK-667: Node.orderBefore() doesn't check whether the node type supports orderable child nodes

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1452746 13f79535-47bb-0310-9956-ffa450edef68
OAK-144: Implement observation
add issue reference

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1452747 13f79535-47bb-0310-9956-ffa450edef68