Enhance - More messages::add updates (#2662)

convert more messages over to messsagse::add

app/call_centers/call_center_agent_delete.php

@@ -93,7 +93,7 @@
 	remove_config_from_cache('configuration:callcenter.conf');
 
 //redirect the browser
-	$_SESSION["message"] = $text['message-delete'];
+	messages::add($text['message-delete']);
 	header("Location: call_center_agents.php");
 	return;