OAK-527: permissions (wip)

- accessmanager#hasPrivilege and #getPrivileges doesn't pass 'null' to permission provider for repo privileges
- permissionvalidatior should also skip hidden nodes
- permissionvalidator lacks special repo-permission handling for properties

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1466069 13f79535-47bb-0310-9956-ffa450edef68