Use logging in the cron module
Fix time hash string function signature

Looks like the self argument got left in when moving it from a module to core module.
Fix file logging
Replace the old stdout log with a proper logfile

Like this:
* we have both output on stdout and in the log file
* output looks nicer and has timestamps
* the log file has all early startup messages, just lite the
  log running in console
Also remove the old debug log module that was handling the stdout log.