Update section names in cloudkitty config

The 'gnocchi_collector' and 'keystone_fetcher' section names were
deprecated in Stein.

Change-Id: I626dc7afe9eabfbeb6c08137a3e6bbeebde2b332

ansible/roles/cloudkitty/templates/cloudkitty.conf.j2

@@ -43,13 +43,13 @@ collector = {{ cloudkitty_collector_backend }}
 metrics_conf = /etc/cloudkitty/{{ cloudkitty_custom_metrics_yaml_file }}
 {% endif %}
 
-[keystone_fetcher]
+[fetcher_keystone]
 keystone_version = 3
 auth_section = keystone_authtoken
 region_name = {{ openstack_region_name }}
 
 {% if cloudkitty_collector_backend == "gnocchi" %}
-[gnocchi_collector]
+[collector_gnocchi]
 auth_section = keystone_authtoken
 region_name = {{ openstack_region_name }}
 {% endif %}