Added full size option to portfolio lightbox images

I've added the ability to include the path to a full size version of the portfolio image, so when it is clicked, a larger version can be displayed. Until the files are approved you can simply copy the functions.php code from here and paste it over the current bigBrands functions.php file.

To use this, simply add the url to the 'caption' field of the image. If no caption is set, the default image url will be used as it has been.

I will post a note once files have been approved.