Specify the Cinder version in the inventory

As described in[1], OpenShift currently only works with Block Storage
API v2 and the version autodetection is failing to figure that out.

[1]: https://github.com/openshift/openshift-docs/issues/5730

playbooks/openstack/sample-inventory/group_vars/OSEv3.yml

@@ -20,6 +20,7 @@ openshift_hosted_registry_wait: True
 #openshift_cloudprovider_openstack_password: "{{ lookup('env','OS_PASSWORD') }}"
 #openshift_cloudprovider_openstack_tenant_name: "{{ lookup('env','OS_TENANT_NAME') }}"
 #openshift_cloudprovider_openstack_region: "{{ lookup('env', 'OS_REGION_NAME') }}"
+#openshift_cloudprovider_openstack_blockstorage_version: v2
 
 
 ## Use Cinder volume for Openshift registry: