malformed command in Keystone Register Identity Providers

When using Keystone federation with OpenID the `Register Identity Providers in OpenStack` task fails with:

openstack: '--os-user-domain-name ${DOMAIN} identity provider create --description ${DESCRIPTION} --remote-id ${REOMOTEID} --domain default ${IDP}' is not an openstack command.

It appears that there is a missing `=` after ` --os-user-domain-name`

In other words this:
```
- name: Register Identity Providers in OpenStack
  become: true
  command: >
    docker exec -t keystone openstack
    --os-auth-url={{ openstack_auth.auth_url }}
    --os-password={{ openstack_auth.password }}
    --os-username={{ openstack_auth.username }}
    --os-identity-api-version=3
    --os-interface={{ openstack_interface }}
    --os-system-scope={{ openstack_auth.system_scope }}
    --os-user-domain-name{{ openstack_auth.user_domain_name }}
    --os-region-name={{ openstack_region_name }}
    {% if openstack_cacert != '' %}--os-cacert={{ openstack_cacert }}{% endif %}
    identity provider create
    --description "{{ item.public_name }}"
    --remote-id "{{ item.identifier }}"
    --domain "{{ item.openstack_domain }}"
    {{ item.name }}
  run_once: True
  when:
    - item.name not in existing_idps
  with_items: "{{ keystone_identity_providers }}"
```

Should be this:
```
- name: Register Identity Providers in OpenStack
  become: true
  command: >
    docker exec -t keystone openstack
    --os-auth-url={{ openstack_auth.auth_url }}
    --os-password={{ openstack_auth.password }}
    --os-username={{ openstack_auth.username }}
    --os-identity-api-version=3
    --os-interface={{ openstack_interface }}
    --os-system-scope={{ openstack_auth.system_scope }}
    --os-user-domain-name={{ openstack_auth.user_domain_name }}
    --os-region-name={{ openstack_region_name }}
    {% if openstack_cacert != '' %}--os-cacert={{ openstack_cacert }}{% endif %}
    identity provider create
    --description "{{ item.public_name }}"
    --remote-id "{{ item.identifier }}"
    --domain "{{ item.openstack_domain }}"
    {{ item.name }}
  run_once: True
  when:
    - item.name not in existing_idps
  with_items: "{{ keystone_identity_providers }}"
```