Fix searchlight nova resources indexation

* nova_server resources resources are not actually
indexed.

* nova flavor are not indexed too, cause the notifications topic for
flavors is versioned_notifications.
We need to config notifications_topics_exchanges with value
'versioned_notifications,nova' in order to get the related versioned.

Change-Id: Ibf4ee7d7efceee5aefac5f83e22b994ae33ce047
Closes-Bug: #1703435

ansible/roles/searchlight/templates/searchlight.conf.j2

@@ -73,7 +73,7 @@ enabled = {{ enable_swift | bool }}
 [resource_plugin:os_swift_object]
 enabled = {{ enable_swift | bool }}
 
-[resource_plugin:os_server_nova]
+[resource_plugin:os_nova_server]
 enabled = {{ enable_nova | bool }}
 
 [resource_plugin:os_nova_hypervisor]
@@ -81,6 +81,7 @@ enabled = {{ enable_nova | bool }}
 
 [resource_plugin:os_nova_flavor]
 enabled = {{ enable_nova | bool }}
+notifications_topics_exchanges = versioned_notifications,nova
 
 [resource_plugin:os_nova_servergroup]
 enabled = {{ enable_nova | bool }}