provider/triton: Add metadata key for cloud-init

Under joyent/triton, the cloud-init cloud-config data actually comes out
of a key called cloud-init:user-data, as opposed to to the standard
user-data. This will make it possible to send the cloud-config data to
triton machines.

Documentation reference: https://docs.joyent.com/public-cloud/instances/virtual-machines/images/linux/ubuntu-certified#cloud-init-examples

builtin/providers/triton/resource_machine.go

@@ -23,6 +23,7 @@ var (
 		"user_script":          "user-script",
 		"user_data":            "user-data",
 		"administrator_pw":     "administrator-pw",
+		"cloud_config":         "cloud-init:user-data",
 	}
 )
 
@@ -182,6 +183,12 @@ func resourceMachine() *schema.Resource {
 				Optional:    true,
 				Computed:    true,
 			},
+			"cloud_config": {
+				Description: "copied to machine on boot",
+				Type:        schema.TypeString,
+				Optional:    true,
+				Computed:    true,
+			},
 			"user_data": {
 				Description: "Data copied to machine on boot",
 				Type:        schema.TypeString,

website/source/docs/providers/triton/r/triton_machine.html.markdown

@@ -77,6 +77,9 @@ The following arguments are supported:
 * `administrator_pw` - (string)
     The initial password for the Administrator user. Only used for Windows virtual machines.
 
+* `cloud_config` - (string)
+    Populate the cloud-init:user-data field. Cloud config data to pass to the instance. Traditionally user-data is used, however joyent uses that key for their own purposes. At least on ubuntu cloud-init, it expects the cloud_config to be in cloud-init:user-data instead of just user-data.
+
 The nested `nic` block supports the following:
 * `network` - (string, Optional)
     The network id to attach to the network interface. It will be hex, in the format: `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`.