Version for showing Amazon S3 storage

Hello, this looks like a rather big change because I have cleaned up the app/assets dir and moved the library js to vendor/assets. I have also removed the old template code in the gallery/views/show.rb which was no longer being used as the logic was moved to main.js. 

Now expecting a merge as this is a different sample, but changes for moving assets to vendor dir and removing stale template code can be safely merged with the original one one. 

It would be great if you could add a short link to this project in the original readme pointing out a s3 sample. :)