title: Voyager admin menu isn't shown for user with role "admin" with all permissions
body: <p>I've created new user by regular "Register" link at app frontend, then issued</p>
  
  <pre><code>php artisan voyager:admin this_user@mail.com
  </code></pre>
  
  <p>and logged in to Voyager with this user's login and password. What I saw is empty space in the panel on the left instead of admin menu:
  <a href="https://i.stack.imgur.com/ri62j.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ri62j.png" alt="enter image description here"></a></p>
  
  <p>I've checked roles and permissions in database. In <code>users</code> table this user has <code>role_id</code> set to <code>1</code>, which is "admin" in table <code>roles</code> and has all permissions in <code>permission_role</code>. This seems to be OK.</p>
  
  <p>Why this user doesn't see the admin menu?</p>