HG-332 Fix links being returned when they should not

@inez Yes it is odd. See here the function that parseLink ultimately calls: https://github.com/Wikia/app/blob/dev/extensions/wikia/WikiaPhotoGallery/WikiaPhotoGalleryHelper.class.php#L187

$link is expected to be either an article title (string) or a URL. If it's a URL it's assumed to be an external URL (to other site or other wiki). When it's not a URL the method just returns the same local URL that was passed in.