title: How to add new apps folder in Yii2 advanced
body: <p>I start install Yii 2 with yii-advanced-app-2.0.11.tgz archive. After unpacking and init, i have run successful Yii 2 advanced. In folder project, i see backend and frontend application. 
  Now, i wanna create clinic application is here. Yii 2 can do it?. I search google, but can't find solution.</p>
  
  <ul>
  <li>backend &amp; frontend</li>
  <li>clinic (How can do it?) </li>
  </ul>
  
  <p>and then I copy frontend directories and name it "clinic" then replace all words "frontend" to "clinic". but I get error like this:</p>
  
  <pre><code>An Error occurred while handling another error:
  exception 'yii\base\InvalidRouteException' with message 'Unable to resolve the request "site/error".' in R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\base\Module.php:532
  Stack trace:
  #0 R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\web\ErrorHandler.php(95): yii\base\Module-&gt;runAction('site/error')
  #1 R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\base\ErrorHandler.php(111): yii\web\ErrorHandler-&gt;renderException(Object(yii\web\NotFoundHttpException))
  #2 [internal function]: yii\base\ErrorHandler-&gt;handleException(Object(yii\web\NotFoundHttpException))
  #3 {main}
  Previous exception:
  exception 'yii\base\InvalidRouteException' with message 'Unable to resolve the request "".' in R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\base\Module.php:532
  Stack trace:
  #0 R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\web\Application.php(102): yii\base\Module-&gt;runAction('', Array)
  #1 R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\base\Application.php(380): yii\web\Application-&gt;handleRequest(Object(yii\web\Request))
  #2 R:\xampp-1-8\htdocs\berobat.id\klinik\web\index.php(17): yii\base\Application-&gt;run()
  #3 {main}
  
  Next exception 'yii\web\NotFoundHttpException' with message 'Page not found.' in R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\web\Application.php:114
  Stack trace:
  #0 R:\xampp-1-8\htdocs\berobat.id\vendor\yiisoft\yii2\base\Application.php(380): yii\web\Application-&gt;handleRequest(Object(yii\web\Request))
  #1 R:\xampp-1-8\htdocs\berobat.id\klinik\web\index.php(17): yii\base\Application-&gt;run()
  #2 {main}
  </code></pre>
  
  <p>in my perception, this is about setting config <code>namespaceController="clinic/controllers"</code>, when I change it to "frontend/controller" this error <code>exception 'yii\base\InvalidRouteException' with message 'Unable to resolve the request "site/error".'</code> not showing anymore, but you know, if still in this config, my clinic apps will load frontend controller. So what should I do? Help me please!. Thanks so much!.</p>