title: Django admin action with intermediate page: not getting info back
body: <p>I'm trying to create an admin action that adds a custom time delta to some date. The time delta will be read from a input in the intermediate page. After confirming it, I will apply that delta to every instance selected previously. Using this code (I simplified for this question) I can't get the value of the entered time delta. I can't tell whether the user pressed the "Apply" button.</p>
  
  <p>models.py</p>
  
  <pre><code>class Match(models.Model):
      date_of_match=models.DateTimeField()
  </code></pre>
  
  <p>admin.py</p>
  
  <pre><code>class MatchAdmin(admin.ModelAdmin):
      actions=('move_date',)
  def move_date(self,request,queryset):
      if 'apply' in request.POST:
          #to do, add timedelta to date_of_match
          print("I'M IN!")
      return render(request.'admin/move_date.html',{'matches':queryset})
  move_date.short_description="Move date"
  </code></pre>
  
  <p>move_date.html</p>
  
  <pre><code>{% extends "admin/base_site.html" %}
  {% block content %}
  &lt;form action="" method="post"&gt;{% csrf_token %}
      &lt;p&gt;How much delta?&lt;p&gt;
      &lt;input type="number" step="1" value="days"/&gt;
      &lt;input type="hidden" name="action" value="move_date" /&gt;
      &lt;input type="submit" name="apply" value="Apply"/&gt;
  &lt;/form&gt;
  {% endblock %}
  </code></pre>