Remove noisy Slack default user warning; refs #560

apprise/plugins/NotifySlack.py

@@ -316,10 +316,6 @@ class NotifySlack(NotifyBase):
                 self.logger.warning(msg)
                 raise TypeError(msg)
 
-        if not self.user:
-            self.logger.warning(
-                'No user was specified; using "%s".' % self.app_id)
-
         # Look the users up by their email address and map them back to their
         # id here for future queries (if needed). This allows people to
         # specify a full email as a recipient via slack