Add Client Class in Command Pattern.

Command/Client.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace DesignPatterns\Command;
+
+/**
+ * Client is responsible for creating a ConcreteCommand and setting its a Receiver
+ */
+class Client
+{
+    /**
+     * Creates a ConcreteCommand object, sets its receiver and test invoker
+     */
+    public function run()
+    {
+        $receiver = new Receiver();
+        $helloCommand = new HelloCommand($receiver);
+
+        $invoker = new Invoker();
+        $invoker->setCommand($helloCommand);
+        $invoker->run();
+    }
+}