[Reviewer: Graeme] Craft logging Enhanced Node Troubleshooting 

Added PDLog infrastructure (definition in new header, craft_dcea.h) and PDLogs for http and sip.
I had a look at this while I was out in Richardson and couldn't come up with a better solution.  To be honest, I think gcc is generally being overzealous with this warning - basically it occurs whenever you use a variable format string.  The only alternative I could see was to turn off the warning globally, but people were nervous about this.