Deprecate or remove TreeCacheProviderHook

Have a discussion and decide to either deprecate or remove the old CacheProvider-based Hibernate/JBC integration.

If we're going to keep it around, extract the basic code into a non-EJB3 lib in repos/jbossas/projects/cluster and have TreeCacheProviderHook and OptimisticTreeCacheProvider hook be trivial extensions that just provide the legacy class names. The basic code is a fairly good Hibernate 3.2 / JBC 2.1 integration layer that doesn't exist elsewhere.