Ignore error on private channel join (slack) Fixes #150

bridge/slack/slack.go

@@ -79,9 +79,11 @@ func (b *Bslack) JoinChannel(channel string) error {
 		}
 		_, err := b.sc.JoinChannel(channel)
 		if err != nil {
+			if err.Error() != "name_taken" {
 				return err
 			}
 		}
+	}
 	return nil
 }