Multi preview for Arlima Article

When width of preview is set as an Array it will render multiple iframes with given widths given the possibility to preview article on different screen resolutions.

Usage:

     /*
      * Define the preview width of specific lists.
      */
      function my_arlima_tmpl_width( $preview_width, $list ) {
        $preview_width = array(658,320);
        return $preview_width;
      }
      add_filter('arlima_tmpl_width', 'my_arlima_tmpl_width', 10, 2);

![screen shot 2014-10-03 at 12 58 55](https://cloud.githubusercontent.com/assets/2885298/4504866/508c59de-4aec-11e4-8cb0-2bb7500f40f5.png)