Revision 161390

Add a new "findbugs" target to build.xml to run the FindBugs tool
<http://findbugs.sourceforge.net>.  Cool tool!

Clean up several issues reported by findbugs -- including a real functionality
bug in TokenProcessor due to a botched copy-n-paste exercise.

The remaining nine warnings are all related to the fact that the
org.apache.commons.chain.impl.ContextBase class "extends HashMap" instead of
"extends AbstractMap", and therefore inherits the "implements Serializable"
characteristic of HashMap.  It's pretty dubious whether Context implementations
should be *required* to be Serializable, but this needs to be discussed on the
Commons Dev list.