[Reviewer: Graeme] Craft logging Enhanced Node Troubleshooting 

Added PDLog infrastructure (definition in new header, craft_dcea.h) and PDLogs for http and sip.
This is dangerous and not necessary. It's dangerous because POSIX doesn't guarantee the order of the signals, or even how many they are. It's not necessary because you can just use strsignal (which is defined in string.h and does exactly what you want).