Easily replace Visual Composer grid columns with Twitter Boostrap columns

vc-twotterbootstrap-grid.php

<?php

add_filter('vc_shortcodes_css_class', function ($class_string, $tag) {
  $tags_to_clean = [
	  'vc_row',
	  'vc_column',
	  'vc_row_inner',
	  'vc_column_inner'
  ];
  if (in_array($tag, $tags_to_clean)) {
	
	  $class_string = str_replace(' wpb_row', '', $class_string);
	  $class_string = str_replace(' vc_row-fluid', '', $class_string);
	  $class_string = str_replace(' vc_column_container', '', $class_string);
	  $class_string = str_replace('wpb_column', '', $class_string);
	  
          // replace vc_, but exclude any custom css 
          // attached via vc_custom_XXX (negative lookahead)
	  $class_string = preg_replace('/vc_(?!custom)/i', '', $class_string);
          
          // replace all vc_
          // $class_string = preg_replace('/vc_/i', '', $class_string);
  }
  $class_string = preg_replace('|col-sm|', 'col-sm', $class_string);
  return $class_string;
}, 10, 2);