OAK-1393 Upgrade Jackrabbit dependency to include JCR-3720 and JCR-3723
 - jackrabbit dependency to 2.8-SNAPSHOT



git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1565145 13f79535-47bb-0310-9956-ffa450edef68