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

test/Microsoft.SqlTools.ServiceLayer.Test/QueryExecution/Common.cs

@@ -184,6 +184,10 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.QueryExecution
             connectionMock.Protected()
                 .Setup<DbCommand>("CreateDbCommand")
                 .Returns(CreateTestCommand(data, throwOnRead));
+            connectionMock.Setup(dbc => dbc.Open())
+                .Callback(() => connectionMock.SetupGet(dbc => dbc.State).Returns(ConnectionState.Open));
+            connectionMock.Setup(dbc => dbc.Close())
+                .Callback(() => connectionMock.SetupGet(dbc => dbc.State).Returns(ConnectionState.Closed));
 
             return connectionMock.Object;
         }