OAK-1155 PropertyIndex cost calculation is faulty
 - pushed the traversal fallback flag to the query, this allows for the distinction between the defined query indexes and the traversal one which should neved be picked if there's a valid query index available




git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1539990 13f79535-47bb-0310-9956-ffa450edef68