title: Django: Naive datetime on query
body: <p>I'm trying to retrieve all data between two dates (monday -> monday). Here's my code:</p>
  
  <pre><code>    some_day_last_week = datetime.datetime.now() - timedelta(days=7)
      monday_of_last_week = some_day_last_week - timedelta(days=(some_day_last_week.isocalendar()[2] - 1))
      monday_of_this_week = monday_of_last_week + timedelta(days=7)
  
      print "Someday last week %s" % some_day_last_week
      print "Monday of last week %s" % monday_of_last_week
      print "Monday of this week %s" % monday_of_this_week
      jobs = Jobs.objects.filter(created_time__gte=monday_of_last_week, created_time__lt=monday_of_this_week).order_by('-created_time')
  
      for job in jobs:
          print "Jobb: %s (%s)" % (job, job.created_time)
  </code></pre>
  
  <p>The output is fine, but I'm getting a RuntimeWarning which is bugging me. Here's that (as well as the other output):</p>
  
  <pre><code>Someday last week 2013-03-14 15:11:32.819508
  Monday of last week 2013-03-11 15:11:32.819508
  Monday of this week 2013-03-18 15:11:32.819508
  xxx/venv/lib/python2.7/site-packages/django/db/models/fields/__init__.py:808: RuntimeWarning: DateTimeField received a naive datetime (2013-03-11 15:11:32.819508) while time zone support is active.
  </code></pre>
  
  <p>RuntimeWarning)
      xxx/venv/lib/python2.7/site-packages/django/db/models/fields/<strong>init</strong>.py:808: RuntimeWarning: DateTimeField received a naive datetime (2013-03-18 15:11:32.819508) while time zone support is active.
    RuntimeWarning)
      Jobb: Webdesigner (2013-03-13 09:14:02+00:00)
      [21/Mar/2013 15:11:32] "GET /jobs/feed/7days/ HTTP/1.1" 200 712</p>
  
  <p>I have USE_TZ set to True in settings.py, and the field created_time is like this:</p>
  
  <pre><code>created_time = models.DateTimeField(_('Creation time'), default=datetime.now)
  </code></pre>
  
  <p>Anyone? :)</p>