Add custom logging setup for daemons

It's better for daemons if:
  - they log only to one log file
  - the log level is included
  - for debug runs, the filename/line number is included

This patch moves the custom formatter from the watcher to the logging
module and generalizes it; then it changes the master daemon to use this
function instead of the generic logging (which might be deprecated
anyway in the future).

Reviewed-by: imsnah