/**
*
* Creates an Embed Handler for CodePen Embeds
* Tested on WP 3.7.1
*
*/
wp_embed_register_handler( 'codepen', '/http?:\/\/codepen\.io\/([a-z0-9]+)\/pen\/([a-z0-9]+)/i', 'wp_embed_handler_codepen');
function wp_embed_handler_codepen( $matches, $attr, $url, $rawattr ) {
	$embed = sprintf(
		'<p data-height="268" data-theme-id="0" data-user="%1$s" data-slug-hash="%2$s" data-default-tab="result" class="codepen"><a href="http://codepen.io/%1$s/pen/%2$s">A Pen by %1$s</a> (<a href="http://codepen.io/%1$s">@%1$s</a>) on <a href="http://codepen.io">CodePen</a></p>
		<script async src="//codepen.io/assets/embed/ei.js"></script>',
			esc_attr($matches[1]),
			esc_attr($matches[2])
			);

	return apply_filters( 'embed_codepen', $embed, $matches, $attr, $url, $rawattr );
}