Get jvm and fs metric node stats with multiple nodes. (#455)

Signed-off-by: dblock <[email protected]>

tests/nodes/stats.yaml

@@ -52,6 +52,18 @@ chapters:
         - jvm
     response:
       status: 200
+  - synopsis: Get jvm and fs metric node stats with multiple nodes.
+    path: /_nodes/{node_id}/stats/{metric}
+    method: GET
+    parameters:
+      node_id:
+        - cluster_manager:false
+        - data:true
+      metric:
+        - fs
+        - jvm
+    response:
+      status: 200
   - synopsis: Get statistics for the request_cache.
     path: /_nodes/stats/{metric}/{index_metric}
     method: GET