title: Convert string into timestamp in Hive
body: <p>I have a value '2017-09-27T19:25:15.927-07:00', is there any way to convert this into a timestamp? 
  I use Hive 1.1.0. </p>
  
  <p><code>select unix_timestamp("2017-09-27T19:25:15.927-07:00", "yyyy-MM-ddTHH:mm:ss.SSSX")</code> but it trows <code>Bad date/time conversion format</code></p>
  
  <p><code>select unix_timestamp("2017-09-27T19:25:15.927-07:00", "yyyy-MM-ddTHH:mm:ss.SSSZZZ")</code> but it returns <code>NULL</code></p>