upgrades to terraform version 0.12

[patrickhuber]

I noticed this sample is behind a few versions, this pull request runs :

cd terraform/muti-region
terraform init
terraform 0.12upgrade


cd terraform/single-region
terraform init
terraform 0.12upgrade

I then went in and fixed any places where lists were using the older syntax.

[hashicorp-cla]

All committers have signed the CLA.