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

Allow empty node names in getChildNode() for now. I think it would be better if we could explicitly declare them invalid.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1464652 13f79535-47bb-0310-9956-ffa450edef68
OAK-734 Refactor indexing code to use Editors

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1464659 13f79535-47bb-0310-9956-ffa450edef68