Support cloudstack_template with multiple zones

This issue was originally opened by @larstobi as hashicorp/terraform#13929. It was migrated here as part of the provider split. The original body of the issue is below.

Terraform Version

0.9.1

Affected Resource(s)

cloudstack_template

Terraform Configuration Files

resource "cloudstack_template" "coreos-stable" {
  name         = "coreos-stable"
  display_text = "CoreOS Container Linux Stable"
  format       = "VHD"
  hypervisor   = "XenServer"
  os_type      = "Other 2.6x Linux (64-bit)"
  is_public    = true
  url          = "http://dl.openvm.eu/cloudstack/coreos/x86_64/coreos_production_cloudstack_image-xen.vhd.bz2"
  zone         = ["Zone-1", "Zone-2"]
}

Expected Behavior

I expect terraform to create the template in "Zone-1" and then copy it to "Zone-2" using the copyTemplate API call. (https://cloudstack.apache.org/api/apidocs-4.9/apis/copyTemplate.html)

Actual Behavior

1 error(s) occurred:

* cloudstack_template.coreos-stable: zone must be a single value, not a list

Steps to Reproduce

terraform apply

xanzy / terraform-provider-cloudstack

Support cloudstack_template with multiple zones #1