trying to download single images from imgur produced error. E.g. https://imgur.com/gallery/YcAQlkx
Issue was caused 'http://imgur.com/gallery/<id>/album_images/hit.json?all=true' returns a json with data field containing id of all images contained in the album. But for a single image, data filed is empty. Added `if` condition to check if its empty.
Every now and then, imgur.com goes crazy and gives us a generic title and description (otherwise it looks all fine though).
Simply update the test case to allow for that craziness.
