Initial admin and DR services. (#329)

* Add initial services for admin, tasks, and DR

* Fix up some of the contract interfaces

* Make fields public to allow Json.Net to work

* Fix a couple issues in backup contracts

src/Microsoft.SqlTools.ServiceLayer/DisasterRecovery/DisasterRecoveryService.cs

@@ -0,0 +1,52 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.Hosting.Protocol;
+using Microsoft.SqlTools.ServiceLayer.DisasterRecovery.Contracts;
+using Microsoft.SqlTools.ServiceLayer.Hosting;
+using Microsoft.SqlTools.ServiceLayer.SqlContext;
+using System;
+using System.Threading.Tasks;
+
+namespace Microsoft.SqlTools.ServiceLayer.DisasterRecovery
+{
+    public class DisasterRecoveryService
+    {
+        private static readonly Lazy<DisasterRecoveryService> instance = new Lazy<DisasterRecoveryService>(() => new DisasterRecoveryService());
+
+        /// <summary>
+        /// Default, parameterless constructor.
+        /// </summary>
+        internal DisasterRecoveryService()
+        {
+        }
+
+        /// <summary>
+        /// Gets the singleton instance object
+        /// </summary>
+        public static DisasterRecoveryService Instance
+        {
+            get { return instance.Value; }
+        }
+
+        /// <summary>
+        /// Initializes the service instance
+        /// </summary>
+        public void InitializeService(ServiceHost serviceHost   )
+        {
+            serviceHost.SetRequestHandler(BackupRequest.Type, HandleBackupRequest);
+        }
+
+        /// <summary>
+        /// Handles a backup request
+        /// </summary>
+        internal static async Task HandleBackupRequest(
+            BackupParams backupParams,
+            RequestContext<BackupResponse> requestContext)
+        {
+            await requestContext.SendResult(new BackupResponse());
+        }
+    }
+}