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/Contracts/BackupRequest.cs

@@ -0,0 +1,30 @@
+//
+// 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.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.DisasterRecovery.Contracts
+{
+    public class BackupParams
+    {
+        public string OwnerUri { get; set; }
+
+        public BackupInfo BackupInfo { get; set; }
+    }
+
+    public class BackupResponse
+    {
+        public bool Result { get; set; }
+
+        public int TaskId { get; set; }
+    }
+
+    public class BackupRequest
+    {
+        public static readonly
+            RequestType<BackupParams, BackupResponse> Type =
+                RequestType<BackupParams, BackupResponse>.Create("disasterrecovery/backup");
+    }
+}