Add "debug=False" arg to builtin Tools
IMO, this would be a nice convention to encourage for both builtin and ad-hoc tools: offer a "debug" kwarg, defaulting to False. If set to True, call cherrypy.log as desired. Using a config arg makes it easy for non-programmers; scoping it to each Tool makes debugging easier. Having it be a local arg also means you can check it inline instead of expensively calling a function.