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/ResultSetSubset.cs

@@ -19,6 +19,6 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts
         /// <summary>
         /// 2D array of the cell values requested from result set
         /// </summary>
-        public object[][] Rows { get; set; }
+        public string[][] Rows { get; set; }
     }
 }