OAK-709: Consider moving permission evaluation to the node state level

Move SecureNodeState to o.a.j.oak.core as it should be possible to keep it internal to RootImpl (& friends)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1465572 13f79535-47bb-0310-9956-ffa450edef68