GenericUnWrapper with test (GEOS-6578)

GenericUnWrapper implemented with method reflection, preconfigured unwrap method lookup for several JBoss environments.

https://jira.codehaus.org/browse/GEOS-6578
It's not about the unrwapper caching, is that each unwrapping call gets into a synchronized section, even if the method is already in the cache (later down in the unwrap method), that's why I'm suggesting to use a ConcurrentHashMap instead of a synchronized map + other synchronizations down in the unwrap method