title: sending date time stamps to elasticsearch through python
body: <p>I have 3 of 5 columns of my data that is in pandas to_datetime format:</p>
  
  <pre><code>col1                 col2                col3                col4            a           
  2017-01-01 21:07:57  2017-01-01 21:07:58 2017-01-01 21:07:59 misc_text_data  text
  2017-01-01 21:07:42  2017-01-01 21:07:48 2017-01-01 21:07:49 misc_test_data  text2
  2017-01-01 21:07:33  2017-01-01 21:07:22 2017-01-01 21:07:21 mist_test_fata  fext3
  </code></pre>
  
  <p>How can I send my data to elasticsearch via the elasticsearch.py field? </p>
  
  <p>I am trying to get elasticsearch to recognize the format as timedate stamps so I can do timeline analysis from these dates. </p>
  
  <p>I am currently sending my data like below with no recognition of the times:</p>
  
  <pre><code>mylist = []
  for doc in df_json:
      doc['tag'] = "mytags"
      action = { "_index":"myindexoftimes", "_type": "mytimes", "_source":doc}
      mylist.append(action)
  
  helpers.bulk(es, mylist)
  </code></pre>
  
  <p>Any assistance would be helpful. thank you. </p>