UP-4108 Changes to support CAS ClearPass in clustered uPortal environment

https://issues.jasig.org/browse/UP-4108

Allows using RMI Replicated Caching with uPortal for CAS ClearPass in Clustered environment so a CAS PGTIOU->PGT ticket that is sent to another uPortal server in the cluster will have the object replicated into the cache of all servers before the server the user is on attempts to look up the PGT from the PGTIOU.

- Changes NaturalIdQuery to specifically name cache to use because auto-generated cachename is {entity-name}##NaturalId and RMI URLs don't allow # characters (even though the ##NaturalId caches were not being replicated, the RMI Caching code threw exceptions)
- Added configuration to filters files and ehcache.xml