title: Change Django date time field auto_now_add format
body: <p>I want to know if there is any way to change Django <strong>dateTimeField</strong> format, I want to set the time using <code>auto_now_add</code> attribute but I can't get it to save it with the format I want. I know that there is a way suing <code>models.DateField</code> but I need to use <code>auto_now_add</code>. Thanks</p>