title: render a null value with a select/drop-down on blade
body: <p>From the "Form" laravelcollective manual:</p>
  
  <blockquote>
    <p>Generating a Drop-Down List With an Empty Placeholder This will create an "option" element with no value as the very first option of
    your drop-down.</p>
    
    <p>echo Form::select('size', ['L' => 'Large', 'S' => 'Small'], null,
    ['placeholder' => 'Pick a size...']);</p>
  </blockquote>
  
  <p>My code on a blade page:</p>
  
  <pre><code>{{ Form::select('company_id', $companies-&gt;pluck('name','id'), null , ['id'=&gt;'company_id','class' =&gt; 'form-control']) }}
  </code></pre>
  
  <p>It render:</p>
  
  <pre><code>&lt;select id="company_id" class="form-control" name="company_id"&gt;
       &lt;option value="1"&gt;azienda1&lt;/option&gt;
       &lt;option value="2"&gt;azienda2&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>why there is no null value? where im wrong?
  thanks in advance!</p>