title: how to change api_token column in token guard
body: <p><strong>Laravel 5.5</strong></p>
  
  <p>I want to change direction of api token that used in <strong>TokenGaurd</strong> so,
  i created a custom guard named <strong>CafeTokenGaurd</strong> extends TokenGuard, i define  __construct function into it like what i want, something like this:</p>
  
  <pre><code>public function __construct(UserProvider $provider, Request $request) {
          parent::__construct($provider, $request);
          $this-&gt;inputKey = 'api_key'; // I want changing this part
          $this-&gt;storageKey = 'api_key';
      }
  </code></pre>
  
  <p>Now i want to define <code>api_key</code> from relation with users table like this:</p>
  
  <pre><code>device_user table -&gt; token
  </code></pre>
  
  <p>i want to define specific tokens for each devices user have, and i want to set api key input and storage key to this column in pivot table between users and devices,</p>
  
  <p>how i should this?!</p>
  
  <p>Thanks</p>