Escape single quote and backslash when writing GUIDs as byte arrays.

[adampoit]

This code is copied from writing a byte array.

These byte values were not escaped when writing a GUID as a byte array, causing syntax errors when doing something like

var query = @"insert into table(value) select @value from dual";
database.Connection.Execute(query, new { value = Guid.NewGuid() });

when OldGuids=true.

Since the code is duplicated, I can refactor it into a method if we feel that's appropriate.

[bgrainger]

Fixed in 0.19.5.