OAK-51 : Access Control Management (WIP)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1437630 13f79535-47bb-0310-9956-ffa450edef68
OAK-50 : Implement User Management

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1437632 13f79535-47bb-0310-9956-ffa450edef68