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/TaskServices/Contracts/TaskInfo.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Microsoft.SqlTools.ServiceLayer.TaskServices.Contracts
+{
+    public enum TaskState
+    {
+        NotStarted = 0,
+        Running = 1,
+        Complete = 2
+    }
+
+    public class TaskInfo
+    {
+        public int TaskId { get; set;  }
+
+        public TaskState State { get;  set; }
+    }
+}