Fix literal not terminated
Fix literal not terminated

Lack of quotation made Terraform to fail miserably crying about
```
invalid value "paas-cf/terraform/prod.tfvars" for flag -var-file: Error
parsing paas-cf/terraform/prod.tfvars: At 82:20: literal not terminated
```

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf