Add the option to ignore certain images based on a given class name.

I was using imagefit for my jQuery Cycle2 slideshow and ran into an issue when trying to utilise the thumbnail pagination in Cycle2. http://jquery.malsup.com/cycle2/demo/pager.php

The gallery of thumbnails were nested **inside** the gallery and absolutely positioned. This caused imagefit to affect these thumbnails too, which led to an undesired result.