Automatically create S3 bucket and CF distribution

[kylefox]

There should be a way to automatically create S3 bucket + CloudFront distribution when a Kirby site is created.

Some ideas:

1. Create AWS services when kirby site is created:

kirby new example.com

2. Have another command for creating AWS services:

kirby aws init

In either case, we probably want to prompt the user to enter the S3 bucket name (defaulting to site) and handle the case where the S3 bucket already exists.

For now it would be easiest to store this information in a hidden YAML file, .aws_config

bucket: example.com
dist_id: d1234abc.net