Format Cell Values (#62)

* WIP for ability to localize cell values

* Changing how DateTimeOffsets are stored, getting unit tests going

* Reworking BufferFileStreamWriter to use dictionary approach

* Plumbing the DbCellValue type the rest of the way through

* Removing unused components to simplify contract

* Cleanup and making sure byte[] appears in parity with SSMS

* CR comments, small tweaks for optimizing LINQ

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

@@ -0,0 +1,23 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
+{
+    /// <summary>
+    /// Class used for internally passing results from a cell around.
+    /// </summary>
+    public class DbCellValue
+    {
+        /// <summary>
+        /// Display value for the cell, suitable to be passed back to the client
+        /// </summary>
+        public string DisplayValue { get; set; }
+
+        /// <summary>
+        /// The raw object for the cell, for use internally
+        /// </summary>
+        internal object RawObject { get; set; }
+    }
+}