Currently, in debug mode, both the logfile handler and the stderr
handler will log debug messages. Since the stderr is redirected to the
same logfile (to catch non-logged errors), it means log entries are
doubled.

The patch adds an extra parameter to the logger.SetupDaemon() function
that allows disabling of the stderr logging. The master and node daemon
will use this to enable stderr logging only when running in foreground.

Reviewed-by: imsnah