MAGETWO-42038: RCE/DOS via cron.php

- Fixed the issue of running the cron without any group (it was showing the error message that you can't run it from cli - which is wrong).

Author: safwkhan

pub/cron.php

@@ -11,12 +11,12 @@
 
 require dirname(__DIR__) . '/app/bootstrap.php';
 
-if ($_GET){
-    $opt = $_GET;
-} else {
+if (php_sapi_name() === 'cli'){
     echo "You cannot run this from the command line." . PHP_EOL .
         "Run \"php bin/magento cron:run\" instead." . PHP_EOL;
     exit(1);
+} else {
+    $opt = $_GET;
 }
 
 try {