OAK-779: Add rep:Authorizable to declaringNodeTypeNames of rep:principalName index

It's no longer necessary to list subtypes in the declaringNodeTypeNames property of an index definition.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1471328 13f79535-47bb-0310-9956-ffa450edef68