OAK-1604 - Support for signed references in Blob (WIP)

Port the org.apache.jackrabbit.core.value.ReferenceBinaryTest to Oak. The test is run with two fixture for SegmentStore and DocumentNodeStore backed by FileDataStore

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1581720 13f79535-47bb-0310-9956-ffa450edef68