"Error submitting webform submission..." error message appears to end users

When using this module to submit webform data to salesforce, an error message "Error submitting webform submission...." appears should the salesforce export fail for some reason. This is in addition to it being saved to the log file. I really don't want the users of my site knowing anything about the salesforce problem because it means nothing to them, and the submission can be retried on next cron run if necessary. So the attached patch simply removes the call to drupal_set_message() - the error message still goes to watchdog() though.