Final Castor XML to JaxB conversion

[Dain Sundstrom]

I'm working on converting the org.apache.openejb.config.sys from  
Castor XML to JaxB.  I believe this is our last required dependency  
on Castor (there is an optional Castor CMP implementation), so when I  
finish we will be able to remove the castor jars and dependencies  
from our build.  Also, this should simplify code that uses these  
classes as JaxB means the introduction of Generics and java  
collections classes.

If you have any concerns, let me know sooner rather than later.
-dain