Require Jackson 2.0+, EhCache 2.5+, Quartz 2.1.4+

Issue: SPR-11262
Improve shutdown responsiveness of SubProtocolWSH

Proactively notify all active WebSocket sessions when a shutdown is
progress. Sessions then can ignore further attempts to send messages
and also stop stop trying to flush messages right away.
Optimize STOMP encoding/decoding hotspots
Polish