Before this patch, all the available Ansible variables for each
validations coming from tripleo-validations were considered as
'metadata' which should only contain the following informations:
```
vars:
metadata:
name: ...
description: ...
groups: ...
```
This patch clarifies this by classifying all the potential variables as
'parameters' instead of 'metadata'.
Change-Id: I7b65b73722ebe0462eb86265197b456e8c77ed13
Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>