Build a replacement for the s3_website deployment tool

[mscottford]

We're currently deploying the site using the s3_website Docker container, but it frequently has problems with invalidating the CloudFront cache, which can cause the deployment to fail. The setting that controls the retry timeout for invalidation does not appear to be something that can be set, however.

As an alternative, I propose switching to a custom script that wraps the s3cmd's sync feature. It also has support for invalidating the s3 cache and can even be used to create 301 redirects as per #2.