Feature/timestamp messages (#68)

* added support for timestamps

* fixed tests

* Moved message class to own file; added 'z' to end of date strings

* added default time constructor

* removed unnecessary z

* added time string format info in comment

* changed from utc time to using local time

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Contracts/ResultMessage.cs

@@ -0,0 +1,44 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+
+namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
+{
+    /// <summary>
+    /// Result message object with timestamp and actual message
+    /// </summary>
+    public class ResultMessage
+    {
+        /// <summary>
+        /// Timestamp of the message
+        /// Stored in UTC ISO 8601 format; should be localized before displaying to any user
+        /// </summary>
+        public string Time { get; set; }
+
+        /// <summary>
+        /// Message contents
+        /// </summary>
+        public string Message { get; set; }
+
+        /// <summary>
+        /// Full constructor
+        /// </summary>
+        public ResultMessage(string timeStamp, string message)
+        {
+            Time = timeStamp;
+            Message = message;
+        }
+
+        /// <summary>
+        /// Constructor with default "Now" time
+        /// </summary>
+        public ResultMessage(string message)
+        {
+            Time = DateTime.Now.ToString("o");
+            Message = message;
+        }
+    }
+}