Can now specify Id on BulkParameters to override the id on the object that was passed

Author: Mpdreamz

src/Nest/Domain/Parameters/BulkParameters.cs

@@ -14,6 +14,7 @@ public class BulkParameters<T> where T : class
 	{
 		public VersionType VersionType { get; set; }
 		public string Version { get; set; }
+		public string Id { get; set; }
 		public string Routing { get; set; }
 		public string Parent { get; set; }
 

src/Nest/ElasticClient-Bulk.cs

@@ -236,8 +236,10 @@ private string GenerateBulkCommand<T>(IEnumerable<BulkParameters<T>> @objects, s
 					continue;
 
 				var objectAction = action;
-
-				objectAction += ", \"_id\" : \"{0}\" ".F(this.Infer.Id(@object.Document));
+				if (!@object.Id.IsNullOrEmpty())
+					objectAction += ", \"_id\" : \"{0}\" ".F(@object.Id);
+				else 
+					objectAction += ", \"_id\" : \"{0}\" ".F(this.Infer.Id(@object.Document));
 
 				if (!@object.Version.IsNullOrEmpty())
 					objectAction += ", \"version\" : \"{0}\" ".F(@object.Version);