title: Sort order in PyES
body: <p>In PyES, i'm executing the following command:
  <code>conn.search(query=_query, indices=self.index_name, doc_types=[self.document_type], sort="name")</code></p>
  
  <p>All well, I get a sort on name. However, I cannot find out how to change the order from ASC to DESC whilst sorting. </p>
  
  <p>I've already tried things like:
  <code>sort=[{'name':'desc}]</code> and <code>sort=[{'name':{'order':'desc'}]</code> as per the docs, but this yields no proper sort.</p>
  
  <p>Any ideas on how to get the right sort order?</p>