title: How to add custom attributes to option elements in symfony 2 form builder
body: <p>I am trying to add custom attributes to the option elements using the symfony2 form builder im im not sure that is natively possible. If its not I need to know how i would go about adding the functionality.</p>
  
  <p>Take the following form as an example:</p>
  
  <pre><code>class FooForm extends AbstractType
  {
      public function buildForm(FormBuilderInterface $builder, array $options)
      {
          $builder-&gt;add('user','choice',array(
              'choices' =&gt; array(
                   'designers'=&gt;'designers',
                   '1'=&gt;'mike',
                   '2'=&gt;'carroll',
                   'developers'=&gt;'developers',
                   '3'=&gt;'chase',
                   '4'=&gt;'brett',
                   '5'=&gt;'jordan',
               )
          ));
      }
  }
  </code></pre>
  
  <p>then when rendered i need it to look like:</p>
  
  <pre><code>&lt;select&gt;
      &lt;option value="" disabled="disabled"&gt;designers&lt;/option&gt;
      &lt;option value="1"&gt;mike&lt;/option&gt;
      &lt;option value="2"&gt;carroll&lt;/option&gt;
      &lt;option value="" disabled="disabled"&gt;developers&lt;/option&gt;
      &lt;option value="3"&gt;chase&lt;/option&gt;
      &lt;option value="4"&gt;brett&lt;/option&gt;
      &lt;option value="5"&gt;jordan&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>what i would expect would be something like:</p>
  
  <pre><code>class FooForm extends AbstractType
  {
      public function buildForm(FormBuilderInterface $builder, array $options)
      {
          $builder-&gt;add('user','choice',array(
              'choices' =&gt; array(
                   'designers'=&gt;array(
                        'label'=&gt;'designers',
                        'attr'=&gt;arrry('disabled'=&gt;'disabled')
                   ),
                   '1'=&gt;'mike',
                   '2'=&gt;'carroll',
                   'developers'=&gt;array(
                        'label'=&gt;'developers',
                        'attr'=&gt;arrry('disabled'=&gt;'disabled')
                   ),
                   '3'=&gt;'chase',
                   '4'=&gt;'brett',
                   '5'=&gt;'jordan',
               )
          ));
      }
  }
  </code></pre>
  
  <p>But that doesnt work. So any help on this will be greatly appreciated.</p>