fix #316 no items are instantiated for bulk update response items

Author: Mpdreamz

Diff for: src/Nest.Tests.Integration/Core/Bulk/BulkUpdateTests.cs

@@ -35,6 +35,9 @@ public void BulkUpdateObject()
 			result = this._client.Bulk(descriptor);
 			result.Should().NotBeNull();
 			result.IsValid.Should().BeTrue();
+			result.Items.Count().Should().Be(1000);
+			result.Items.All(i => i != null).Should().BeTrue();
+			result.Items.All(i => i.OK).Should().BeTrue();
 
 			var updatedObject = this._client.Get<ElasticSearchProject>(5000);
 			Assert.NotNull(updatedObject);

Diff for: src/Nest/Domain/Responses/BulkUpdateResponseItem.cs

@@ -0,0 +1,24 @@
+using Nest.Resolvers.Converters;
+using Newtonsoft.Json;
+
+namespace Nest
+{
+	[JsonObject]
+	[JsonConverter(typeof(BulkOperationResponseItemConverter))]
+	public class BulkUpdateResponseItem : BulkOperationResponseItem
+	{
+		public override string Operation { get; internal set; }
+		[JsonProperty("_index")]
+		public override string Index { get; internal set; }
+		[JsonProperty("_type")]
+		public override string Type { get; internal set; }
+		[JsonProperty("_id")]
+		public override string Id { get; internal set; }
+		[JsonProperty("_version")]
+		public override string Version { get; internal set; }
+		[JsonProperty("ok")]
+		public override bool OK { get; internal set; }
+		[JsonProperty("error")]
+		public override string Error { get; internal set; }
+	}
+}

Diff for: src/Nest/Resolvers/Converters/BulkOperationResponseItemConverter.cs

@@ -29,6 +29,12 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
 					if (deleteItem != null)
 						deleteItem.Operation = key;
 					return deleteItem;
+				case "update":
+					var updateItem = new BulkUpdateResponseItem();
+					serializer.Populate(prop.Value.CreateReader(), updateItem);
+					if (updateItem != null)
+						updateItem.Operation = key;
+					return updateItem;
 				case "index":
 					var indexItem = new BulkIndexResponseItem();
 					serializer.Populate(prop.Value.CreateReader(), indexItem);