title: Rails role-based auth with roles stored in database
body: <p>Does exists gem, that implements following things:</p>
  
  <ul>
  <li>User can has many roles</li>
  <li>Each role has group of permissions</li>
  <li>Each permission just boolean</li>
  <li>Roles and permissions stored in database (most important)</li>
  </ul>
  
  <p>For example, I want for something like this:</p>
  
  <pre><code>if current_user.can?(:read_all, :list_of_orders)
  ...
  end
  </code></pre>
  
  <p>And <code>can?</code> method should search, does any of roles allows it.</p>