0.18.0 Fix IPv6 variables. Change AWS region for tests. Fix `enabled` logic. Update LICENSE

what

• Fix IPv6 variables
• Change AWS region for tests
• Fix enabled logic
• Use terraform-null-label instead of terraform-terraform-label
• Update LICENSE

why

• Duplicate ipv6_enabled variables - we need only one flag
• We use us-east-2 region for Terratest now (us-west-1 is very limited region)
• enabled logic for module "dns" was wrong
• terraform-null-label has more features and works without issues in TF 0.12