Define primary hosted zones in code, with CI/CD #67

Similar to that described in #2, we recently had an event where a few people wanted a DNS record and didn't know where to go.

It should be possible to manage DNS records for operationcode.org from within this repository.

To do so:

• Create an S3 bucket for Terraform remote state storage.

• Create AWS user credentials to provide to CircleCI, along with an IAM policy providing access to the bucket for remote state storage.

• Get the DNSimple API key and provide it to CircleCI.

• Use Terraform to define records as they currently exist in DNSimple. DNSimple credentials are in 1Password.

• Run terraform import on all existing resources once the configuration is complete, and run terraform plan to validate. We should see no changes.

• Create a record by adding a new Terraform resource definition, and on merge to master it should apply.

Bonus points if terraform plan is run against the PR prior to merging. Consider using terragrunt.