Play optimizations

- Fix locking in Play classloader
https://github.com/playframework/play1/commit/63e5fbce6bec455b851f9214133916e6b6463d67
http://play.lighthouseapp.com/projects/57987/tickets/1459-blocked-threads-in-applicationclassloader
- JPABase.saveAndCascade will cache annotations
should comment on use of shared lock: "shared lock because we don't know if Play's enhancement is threadsafe"