OAK-2054 - use more efficient query in MissingLastRevSeeker; add test coverage for RDB

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1621192 13f79535-47bb-0310-9956-ffa450edef68
OAK-2059 Reindexing can include hidden nodes in the index

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1621201 13f79535-47bb-0310-9956-ffa450edef68