ISPN-3011 If predefined in cache configuration, use that exclusively

https://issues.jboss.org/browse/ISPN-3011

* Something to be noted in the documentation, but simplifies a lot the way configuration is managed internally in JSR-107, without having to start merging/mapping Infinispan configuration to JCache configuration, particularly taking in account how several aspects are very differently configured (i.e. expiration).