Marvel: Add state_uuid to cluster_state documents

Closes elastic/elasticsearch#750

Original commit: elastic/x-pack-elasticsearch@4005fe0090

marvel/src/main/java/org/elasticsearch/marvel/agent/renderer/cluster/ClusterStateRenderer.java

@@ -20,6 +20,7 @@ public class ClusterStateRenderer extends AbstractRenderer<ClusterStateMarvelDoc
     public static final String[] FILTERS = {
             "cluster_state.version",
             "cluster_state.master_node",
+            "cluster_state.state_uuid",
             "cluster_state.status",
             "cluster_state.nodes",
     };

marvel/src/main/resources/marvel_index_template.json

@@ -178,6 +178,10 @@
               "type": "string",
               "index": "not_analyzed"
             },
+            "state_uuid": {
+              "type": "string",
+              "index": "not_analyzed"
+            },
             "status": {
               "type": "string",
               "index": "not_analyzed"

marvel/src/test/resources/samples/cluster_state.json

@@ -4,6 +4,7 @@
   "cluster_state": {
     "status": "yellow",
     "version": 14,
+    "state_uuid": "lj0hNoO9QaeNa1eR2ukktQ",
     "master_node": "__node_id__",
     "nodes": {
       "__node_id__": {