Set the start to 0 on export

If we don't set the start to 0, if we're press the export button from page > 1, the row index will completely wrong.

Author: nmfzone

src/Services/DataTable.php

@@ -323,7 +323,10 @@ protected function mapResponseToColumns($columns, $type)
      */
     protected function getAjaxResponseData()
     {
-        $this->request()->merge(['length' => -1]);
+        $this->request()->merge([
+            'start' => 0,
+            'length' => -1
+        ]);
 
         $response = app()->call([$this, 'ajax']);
         $data     = $response->getData(true);