OAK-622 Improve QueryIndex interface (use the AdvancedQueryIndex if available) (WIP)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1578285 13f79535-47bb-0310-9956-ffa450edef68
OAK-650: Move SegmentNodeStoreBranch.RebaseDiff to utility package
Test cases

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1578291 13f79535-47bb-0310-9956-ffa450edef68