i also recommend to use codeship,simple and easy, but you need to create IAM user with proper permission (which is policy) to S3 bucket.
the basic plan for codeship is free.
Well there might be a problem so far i can see codeship will not remove files as you remove files in github, after all, s3 is not github repo, but anyway, the putObject operations for lots of github update just works good enough to me.
