title: Compound natural key in DbSet.AddOrUpdate
body: <p>I'm trying to use the CodeFirst data migrations in EF5 with a table that has a composite natural key.  Is it possible to specify this in the first argument to DbSet.AddOrUpdate, like</p>
  
  <pre><code>context.Table1.AddOrUpdate(
       t=&gt;t.Column1 &amp;&amp; t.Column2,
       new Table1 { properties... }
  );
  </code></pre>
  
  <p>How would one specify using more than one property in this case?</p>
  
  <p>Thanks,
  Matthew</p>