Added correct support for date time offsets in Sql Server.

This pull request contains proper support for  <code>DateTimeOffset</code> in SQL Server and fixes the following issues:
* <code>CreateTable</code> was previously creating <code>time</code> coumns.
* Generated sql was incorrect when <code>CurrentCulture</code> was different to the <code>dateformat</code> specified in SQL Server.
    *   e.g CultureInfo is en-AU and  <code>SELECT Bar FROM FOO WHERE ("Bar" <= '13/11/2013 12:00:00 AM +00:00')</code> is generated for use with default dateformat MDY of SQL Server