title: Add admin prefix in usermgmt plugin in cake php
body: <p>i want make separate admin login but not working giving me error for below url</p>
  
  <pre><code>sitename/admin/admin_login
  </code></pre>
  
  <p><strong>Error:</strong></p>
  
  <pre><code>Error: AdminLoginController could not be found.
  
  Error: Create the class AdminLoginController below in file: app/Controller/AdminLoginController.php
  </code></pre>
  
  <p><strong>Cake Php routing setting mention below</strong></p>
  
  <p>app\Plugin\Usermgmt\Config\routes.php</p>
  
  <pre><code>Router::connect('/login', array('plugin' =&gt; 'usermgmt', 'controller' =&gt; 'users', 'action' =&gt; 'login')); // working fine
  Router::connect('/admin_login', array('admin' =&gt; true, 'plugin' =&gt; 'usermgmt', 'controller' =&gt; 'users', 'action' =&gt; 'admin_login')); // not working
  </code></pre>
  
  <p>app\Config\routes.php</p>
  
  <pre><code>Configure::write('Routing.prefixes', array('admin'));
  </code></pre>
  
  <p>app\Plugin\Usermgmt\Controller\UsersController.php(action in controller)</p>
  
  <pre><code>public function admin_login() {
  // here is admin login code
  }
  </code></pre>
  
  <p><strong>My view file path</strong>
  app\Plugin\Usermgmt\View\Users\admin_login.ctp</p>