Removed the bin directory.
Let's call .retrieve on the PhotosetCollection instead of calling .all, since that implies retrieving multiple photoset collections and there's only one with a lot of photosets, so that's a bit confusing.
Added the Kuva::SetsController which show all of the photosets on the index page and the specified photoset on the show page.
Added the Kuva::PhotoController and its view, which shows the photo itself and its details.