title: define input as submit in symfony2
body: <p>How I can set button type as input tag in symfony2?</p>
  
  <pre><code>&lt;input type="submit" id="id_submit" name="click to go next" class="submit"&gt;&lt;/input&gt;
  </code></pre>
  
  <p>using symfony2 formType as 
       public function buildForm(FormBuilderInterface $builder, array $options)
      {</p>
  
  <pre><code>    $builder
  
      -&gt;add('submit', 'button',array('attr' =&gt; array('class'=&gt;'submit','type'=&gt;'input')))
      ;
  }
  </code></pre>
  
  <p>As it shows</p>
  
  <pre><code>&lt;button type="submit" id="ponemonSurvey_submit" name="click here to go" class="submit"&gt;&lt;/input&gt;
  </code></pre>