title: ImageField not getting deleted when save button is pressed : Django-admin
body: <p>i have the following files</p>
  
  <p>models.py</p>
  
  <p>Class Trip(models.Model)</p>
  
  <pre><code>featured = models.BooleanField(default=False, help_text='Tags this trip as a featured trip.')
  top_ten_trip = models.BooleanField(default=False)
  header_image = models.ImageField(help_text='This is the image shown when viewing the details for this trip.', upload_to='images/', blank=True, null=True)
  map_image = models.ImageField(help_text='The map image for this trip.', upload_to='images/', blank=True, null=True)
  .....
  </code></pre>
  
  <p>and so on</p>
  
  <p>admin.py</p>
  
  <p>class TripAdmin(admin.ModelAdmin):</p>
  
  <pre><code>list_display = ('name', 'code', 'category', 'supplier', 'active', 'featured', 'top_ten_trip',)
  search_fields = ('name', 'code',)
  list_filter = ('category', 'featured', 'top_ten_trip',)
  filter_horizontal = ('countries', 'related_trips',)
  </code></pre>
  
  <p>The field appear with browse button in admin something like this
  Header image: Currently: images/comfort_japan.jpg
  Change: Delete this file</p>
  
  <p>Map image: Currently: images/map_japan_.jpg
  Change: Delete this file</p>
  
  <p>Now the Problem :-
  When i click on Delete this imagefile( images/comfort_japan.jpg ) it get removed for that instant but does not deleted when i press save button on admin.</p>
  
  <p>I want when i click on delete this file and press save it should get deleted.</p>
  
  <p>What mistake i am doing or what am i missing ?</p>
  
  <p>Thanks in advance.  </p>