Add support for Ceph monitoring

This change adds support for Ceph monitoring:
- service.monitoring.cluster_stats is applied to monitoring nodes for
  collecting cluster-wide metrics (through the Ceph CLI).
- service.monitoring.node_stats is applied to the Ceph nodes for
  collecting monitor and OSD metrics (through Unix sockets).

Because Telegraf runs as a container on the monitoring nodes and
requires a working Ceph client configuration, this  change also adds
support for deploying Ceph client in container mode.

Change-Id: If7359aca34a350f2c8ee2251bbe8a85314550a45
diff --git a/README.rst b/README.rst
index c34cdc6..a8fa04a 100644
--- a/README.rst
+++ b/README.rst
@@ -65,7 +65,7 @@
           glance:
             key: 00000000000000000000000000000000000000==
 
-Client pillar - ussually located at cinder-volume or glance-registry.
+Client pillar - usually located at cinder-volume or glance-registry.
 
 .. code-block:: yaml
 
@@ -92,6 +92,34 @@
           glance:
             key: 00000000000000000000000000000000000000==
 
+Monitoring Ceph cluster - collect cluster metrics
+
+.. code-block:: yaml
+
+    ceph:
+      client:
+        config:
+          global:
+            mon initial members: ceph1,ceph2,ceph3
+            mon host: 10.103.255.252:6789,10.103.255.253:6789,10.103.255.254:6789
+        keyring:
+          monitoring:
+            key: 00000000000000000000000000000000000000==
+      monitoring:
+        cluster_stats:
+          enabled: true
+          ceph_user: monitoring
+
+Monitoring Ceph services - collect metrics from monitor and OSD services
+
+.. code-block:: yaml
+
+    ceph:
+      monitoring:
+        node_stats:
+          enabled: true
+
+
 Read more
 =========