drop unnecessary tables and module

backend/modules/document/Document.php

@@ -1,24 +0,0 @@
-<?php
-
-namespace backend\modules\document;
-
-/**
- * document module definition class
- */
-class Document extends \yii\base\Module
-{
-    /**
-     * {@inheritdoc}
-     */
-    public $controllerNamespace = 'backend\modules\document\controllers';
-
-    /**
-     * {@inheritdoc}
-     */
-    public function init()
-    {
-        parent::init();
-
-        // custom initialization code goes here
-    }
-}