Add packaging to cluster stats response. (#3995)

This commit adds a packaging_types field to the cluster stats response that outlines the build flavors and types present in a cluster.

(cherry picked from commit 58bbb80)

Author: codebrain

src/Nest/Cluster/ClusterStats/ClusterNodesStats.cs

@@ -12,6 +12,9 @@ public class ClusterNodesStats
 		[DataMember(Name ="discovery_types")]
 		public IReadOnlyDictionary<string, int> DiscoveryTypes { get; internal set; }
 
+		[DataMember(Name ="packaging_types")]
+		public IReadOnlyCollection<NodePackagingType> PackagingTypes { get; internal set; }
+
 		[DataMember(Name ="fs")]
 		public ClusterFileSystem FileSystem { get; internal set; }
 
@@ -34,6 +37,18 @@ public class ClusterNodesStats
 		public IReadOnlyCollection<string> Versions { get; internal set; }
 	}
 
+	public class NodePackagingType
+	{
+		[DataMember(Name ="flavor")]
+		public string Flavor { get; internal set; }
+
+		[DataMember(Name ="type")]
+		public string Type { get; internal set; }
+
+		[DataMember(Name ="count")]
+		public int Count { get; internal set; }
+	}
+
 	[DataContract]
 	public class ClusterNetworkTypes
 	{