ERROR: Template not in valid format: Template format version not found..

[Jacques Malaprade]

Rally version: 0.10.1~dev31
OS: Ubuntu 16.04 LTS

Running the create-and-delete-stack.yaml with the plugin HeatStacks.create_and_delete_stack calling the heat template default.yaml.template

`$ rally task start heat/create-and-delete-stack.yaml --task-args-file args.yaml`

fails with message:

```Reason(s):
 Heat template validation failed on heat/templates/default.yaml.template. Original error message: ERROR: Template not in valid format: Template format version not found..```

create-and-delete-stack.yaml

  HeatStacks.create_and_delete_stack:
    -
      args:
        template_path: "heat/templates/default.yaml.template"
      runner:
        type: "constant"
        times: 5
        concurrency: {{concurr}} #2
      context: {}
      sla:
        failure_rate:
          max: 0

args.yaml

  flavors:
    - "compute-A"
    - "compute-B"
  images:
    - "Ubuntu-16.04"
    - "CentOS-7.4"
  subnet_cidr: "192.168.144.0/24"
  network_name: "rally_testing"
  concurr: 1

default.yaml.template

heat_template_version: 2014-10-16

The above version date is available in the openstack template version using

`openstack orchestration template version list` showing

`| heat_template_version.2014-10-16 | hot | |`

I have checked the format of the heat template using `openstack orchestration template validate -f yaml -t heat/template/server.yaml.template` with no errors.

[Jacques Malaprade (malapradej)]

In addition it is perfectly possible to create a stack using this template and the command:
`$ openstack stack create -t heat/templates/default.yaml.template mystack`

```
+---------------------+--------------------------------------+
| Field | Value |
+---------------------+--------------------------------------+
| id | 2ff30634-0d05-4f4a-8d2e-c8ec12d8d367 |
| stack_name | mystack |
| description | Blank template |
| creation_time | 2017-12-19T08:11:20Z |
| updated_time | None |
| stack_status | CREATE_COMPLETE |
| stack_status_reason | Stack CREATE completed successfully |
+---------------------+--------------------------------------+
```