OAK-396: Limit property index to nodes of given type 

- adjust utilities
- add constant in IndexConstants
- change UserInitializer to specify rep:User and rep:Group as declaring node types
- change AccessControlInitializer: specify ace node types as declaring node types

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1443483 13f79535-47bb-0310-9956-ffa450edef68