OAK-50 : Implement User Management

- resolve TODO related to OAK-343

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1443545 13f79535-47bb-0310-9956-ffa450edef68
OAK-50 : Implement User Management

- resolve TODO related to OAK-343

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1443546 13f79535-47bb-0310-9956-ffa450edef68