Make it compatible with netty 3.6.2.Final

Will work with latest and old netty releases now.

[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] Stilts ............................................ SUCCESS [0.740s]
[INFO] Stilts Stomp Common API ........................... SUCCESS [2.677s]
[INFO] Stilts Stomp Common (Client and Server) ........... SUCCESS [6.397s]
[INFO] Stilts Stomp Client ............................... SUCCESS [4.052s]
[INFO] Stilts STOMP Server SPI ........................... SUCCESS [0.978s]
[INFO] Stilts STOMP Server Core .......................... SUCCESS [11.654s]
[INFO] Stilts Javascript STOMP Client .................... SUCCESS [4.190s]
[INFO] Stilts Ruby STOMP Client (requires JRuby) ......... SUCCESS [7.563s]
[INFO] Stilts Conduit Server SPI ......................... SUCCESS [1.160s]
[INFO] Stilts Conduit Server Core ........................ SUCCESS [4.808s]
[INFO] Stilts Stomplet API ............................... SUCCESS [1.270s]
[INFO] Stilts Stomplet Server Core ....................... SUCCESS [8.897s]
[INFO] Stilts Stomplet Server Bundle ..................... SUCCESS [2.577s]
[INFO] Stilts Stomplet Server Bundle Tests ............... SUCCESS [2.711s]
[INFO] Stilts Stomplet CDI Integration ................... SUCCESS [1.136s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1:03.243s
[INFO] Finished at: Wed Feb 20 12:45:11 CET 2013
[INFO] Final Memory: 119M/1425M
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