fix #627 missing lang parameter on bulk update descriptor

Author: Mpdreamz

Diff for: src/Nest/DSL/BulkUpdateDescriptor.cs

@@ -15,7 +15,7 @@ public class BulkUpdateDescriptor<T, K> : BaseBulkOperation
 		internal override string _Operation { get { return "update"; } }
 		internal override object _Object { get; set; }
 
-		
+		internal string _Lang { get; set; }
 		internal K _Document { get; set; }
 		internal string _Script { get; set; }
 		internal Dictionary<string, object> _Params { get; set; }
@@ -28,6 +28,7 @@ internal override object GetBody()
 			{
 				_Document = this._Document,
 				_Script = this._Script,
+				_Lang = this._Lang,
 				_Params = this._Params,
 				_Upsert = this._Upsert,
 				_DocAsUpsert = this._DocAsUpsert
@@ -114,6 +115,12 @@ public BulkUpdateDescriptor<T, K> DocAsUpsert(bool docAsUpsert = true)
 			return this;
 		}
 
+		public BulkUpdateDescriptor<T, K> Lang(string lang)
+		{
+			this._Lang = lang;
+			return this;
+		}
+
 		public BulkUpdateDescriptor<T, K> Script(string script)
 		{
 			script.ThrowIfNull("script");

Diff for: src/Nest/DSL/UpdateDescriptor.cs

@@ -15,6 +15,8 @@ public partial class UpdateDescriptor<T,K> : DocumentPathDescriptorBase<UpdateDe
 		where K : class
 	{
 
+
+
 		[JsonProperty(PropertyName = "script")]
 		internal string _Script { get; set; }
 
@@ -31,6 +33,7 @@ public partial class UpdateDescriptor<T,K> : DocumentPathDescriptorBase<UpdateDe
 		[JsonProperty(PropertyName = "doc")]
 		internal K _Document { get; set; }
 
+		
 		public UpdateDescriptor<T, K> Script(string script)
 		{
 			script.ThrowIfNull("script");

Diff for: src/Nest/Domain/Bulk/BulkUpdateBody.cs

@@ -21,5 +21,8 @@ internal class BulkUpdateBody<T, K>
 
 		[JsonProperty(PropertyName = "doc_as_upsert")]
 		public bool? _DocAsUpsert { get; set; }
+
+		[JsonProperty(PropertyName = "lang")]
+		public string _Lang { get; set; }
 	}
 }