Commons-logging -> SLF4J

[Jason Dillon]

I would like to move the logging framework from Commons-logging to  
SLF4J.

SLF4J has less classloading wrinkles than JCL and has a smaller foot  
print, while providing more logging features, most significantly its  
fast parser for "{}" replacement which makes the need for most if  
(log.isDebugEnabled()) {} blocks uneeded.

If there are no objections I would like to provide a patch to move  
from JCL to SLF4J.

--jason