Knox wants AWS region us-standard instead of us-east-1 

Knox follows a (AFAIK) non-standard region naming for the US Standard (us-east-1) region, where instead of `us-east-1`, it expects `us-standard`.

Leaving the AWS region as `us-east-1` causes requests to S3 to 404.

This PR modifies the knox config so that if the `AWS_REGION` setting is `us-east-1`, we translate it to `us-standard` just for knox.