Add CoolSMS PHP SDK, and update Composer dependencies

vendor/coolsms/php-sdk/examples/Message/example_cancel.php

@@ -0,0 +1,32 @@
+<?php
+/** 
+ * #example_cancel
+ *
+ * This sample code demonstrate how to cancel reserved sms through CoolSMS Rest API PHP
+ * for more info, visit
+ * www.coolsms.co.kr
+ */
+
+use Nurigo\Api\Message;
+use Nurigo\Exceptions\CoolsmsException;
+
+require_once __DIR__ . "/../../bootstrap.php";
+
+// api_key and api_secret can be obtained from www.coolsms.co.kr/credentials
+$api_key = '#ENTER_YOUR_OWN#';
+$api_secret = '#ENTER_YOUR_OWN#';
+
+try {
+    // initiate rest api sdk object 
+    $rest = new Message($api_key, $api_secret);
+
+    // Either mid or gid must be entered. 
+    $options = new stdClass();
+    $mid = 'M52CB443257C61'; // message id. 
+    $gid = 'G52CB4432576C8'; // group id. 
+
+    $rest->cancel($mid); // if $gid is exists. ex) $rest-cancel(null, $gid);
+} catch(CoolsmsException $e) {
+    echo $e->getMessage(); // get error message
+    echo $e->getCode(); // get 'api.coolsms.co.kr' response code
+}