title: Django: may not be NULL when submitting a form
body: <p>I'm trying to submit a form with just the date(and now time), but when I go to submit it I get the error <code>incidents_incident.incident_date_time_occurred may not be NULL</code> even when I enter an actual date in the input field. Why do I get that error when I enter in a date?</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class Incident(models.Model):
         incident_date_time_occurred = models.DateTimeField('incident occurred', default=timezone.now, blank=True)
      class Meta:
                 verbose_name_plural="Incident"
  </code></pre>
  
  <p><strong>forms.py</strong></p>
  
  <pre><code>class IncidentForm(forms.ModelForm):
  
      class Meta:
          model = Incident
          fields = ('incident_date_time_occurred',)
  </code></pre>
  
  <p><strong>report.html</strong></p>
  
  <pre><code>{% extends "base.html" %}
  
  {% block content %}
  
  &lt;div class="container-fluid"&gt;
  
  &lt;form action="{% url 'incidents:report' %}" method="POST"&gt;{% csrf_token %}
      {% csrf_token %}
  
      &lt;div class="row"&gt;
          &lt;div class="form-group col-md-4"&gt;
              &lt;label for="date" class="col-sm-4 control-label"&gt;{{ form.incident_date_time_occurred.label }}&lt;/label&gt;
              &lt;input type="datetime-local" name= "incident_date_time_occurred" class="form-control" id="date"&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  
      &lt;input type="submit" value="Inschrijven!" class="btn btn-primary" /&gt;
  
  &lt;/form&gt;
  
  &lt;/div&gt;
  {% endblock %}
  </code></pre>