OPENJPA-2027: Metamodel genereated at runtime expects ListAttribute for all arrays - not just PersistentCollections.  Back-ported Mike Dick's trunk changes to 2.1.x; made Compatibility property default to true.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/2.1.x@1469452 13f79535-47bb-0310-9956-ffa450edef68