title: MongoDb timestamp
body: <p>i have created and want to now import a dummy collection. one of the fields in each item are "created" and "updated" fields. what can i put in the source/json file so that MongoDb will use the current date and time as the value on import?</p>
  
  <p>this wont work </p>
  
  <pre><code>"created" : Date()
  </code></pre>