Add module and states for gnocchi

Initial version of the module allows to create/delete/update/list
archive policies and rules.
Also added client states supporting rules and policies creation

Change-Id: I7341dfb26a39275e1a9b55f7a49fd2ace9584612
Related-Prod: https://mirantis.jira.com/browse/PROD-20719
diff --git a/README.rst b/README.rst
index 984d971..0edefad 100644
--- a/README.rst
+++ b/README.rst
@@ -232,6 +232,38 @@
           address: 127.0.0.1
           port: 8125
 
+Gnocchi archive policy definition example:
+
+.. code-block:: yaml
+
+    gnocchi:
+      client:
+        enabled: True
+        resources:
+          v1:
+            enabled: true
+            cloud_name: admin_identity
+            archive_policies:
+              test_policy:
+                definition:
+                  - granularity: '1h'
+                    points: 10
+                    timespan: '10h'
+                  - granularity: '2h'
+                    points: 10
+                    timespan: '20h'
+                aggregation_methods:
+                  - mean
+                  - max
+                back_window: 2
+                rules:
+                  test_policy_rule1:
+                    metric_pattern: 'fo.*'
+                  test_policy_rule2:
+                    metric_pattern: 'foo2.*'
+
+
+
 More Information
 ================