Introduce logging_old.h to move logging.h to libutils
Export GetErrorStr, useful for Log
Use Log in libcfnet, not CfOut
Use logging_old.h for CfOut
Get rid of CfDebug in libcfnet
Split logging into libutils- and libpromises- parts
Merge pull request #581 from dottedmag/master

Split logging into libutils- and libpromises- parts