[WIP] Initial static application infrastructure

[malford]

Terraform templates for https://github.com/adhocteam/soapbox/issues/140

This PR contains the terraform templates to launch the following static application infrastructure:

• Blue s3 bucket
• Green s3 bucket
• Cloudfront distribution
• Route53 record

To launch from local environment:

$ cd ops/aws/terraform/deployment/static
$ terraform apply -var application_name=static-app -var environment=test

to do (tracked in https://github.com/adhocteam/soapbox/issues/138):

• Assets are built for commit sha and uploaded to s3
• Update CloudFront distribution for blue environment by removing S3 bucket CNAME from Alternative Domain Names
• Update CloudFront distribution for green environment by adding S3 bucket CNAME to Alternative Domain Names
• Update Route53 A Alias record with CloudFront distribution Domain Name from green environment