Add support for ObjectId type for the Id of the document.

CoreIntegrationTests/CRUDObjectIdTests.cs

@@ -0,0 +1,22 @@
+using CoreIntegrationTests.Infrastructure;
+using MongoDB.Bson;
+using System;
+namespace CoreIntegrationTests
+{
+    public class CoreObjectIdTestDocument : TestDoc<ObjectId>
+    {
+    }
+
+    public class CRUDObjectIdTests : MongoDbTKeyDocumentTestBase<CoreObjectIdTestDocument, ObjectId>
+    {
+        public CRUDObjectIdTests(MongoDbTestFixture<CoreObjectIdTestDocument, ObjectId> fixture) : base(fixture)
+        {
+
+        }
+
+        public override string GetClassName()
+        {
+            return "CRUDObjectIdTests";
+        }
+    }
+}