Theming simplenews block

simplenews-block-form.tpl.php

<div class="contact_form news-form">
  <div class="container">
    <div class="row">
      <div class="col-sm-12 text-center">
        <h2> <span class="icons-a"><img src="<?php print drupal_get_path('theme', 'bartik');?>/img/news-letter-icon.png" alt="icon"></span> 
        <?php print t("Newsletter");?></h2>
        <p><?php print $heading;?> </p>
      </div>
    </div>
    <div class="row contact_field">
      <div class="sign-up-row clearfix">
        <div class="snp-1">
          <?php print $mail; ?>
        </div>
        <div class="snp-2">
          <?php print $submit; ?>
        </div>
      </div>
    </div>
  </div>
</div>
<?php print $children; ?>

template.php

function bartik_theme() {
  return array(
    'simplenews_block_form_1' => array(      
      'render element' => 'form',
      'template' => 'simplenews-block-form',
      'path' => drupal_get_path('theme', 'bartik').'/templates',
    ),			
  );
} 

function bartik_preprocess_simplenews_block_form_1(&$variables) {
  	// Shorten the form variable name for easier access.
  	$form = $variables['form'];
  	unset($form['mail']['#title']);
  	$form['mail']['#id'] = 'exampleInputEmail1';
  	$form['mail']['#attributes'] = array('class' => array('form-control'));
  	$form['mail']['#attributes']['placeholder'] = t('Enter Your Email');
  	$form['submit']['#value'] = t('Sign Up');
  	$form['submit']['#attributes'] = array('class' => array('licence_btn') );
  	$variables['heading'] = t('Sign up for our Newsletter to receive updates that will help you!'); 
 	// Create variables for individual elements.
	$variables['mail'] = render($form['mail']);
	$variables['submit'] = render($form['submit']);	 
	// Be sure to print the remaining rendered form items.
	$variables['children'] = drupal_render_children($form);
}