title: Incorrect longitude/latitude saved to PointField via admin widget
body: <p>I have a basic GeoDjango <code>PointField</code>:</p>
  
  <pre><code>point = models.PointField(srid=4326, null=True)
  </code></pre>
  
  <p>When using the admin, I would expect this to be saved in the database as (for example, London):</p>
  
  <pre><code>SRID=4326;POINT (-94.577597, 39.057294)
  </code></pre>
  
  <p>but instead, if I place the marker on London, I get:</p>
  
  <pre><code>SRID=4326;POINT (-19067.91721243037 6711435.410105047)
  </code></pre>
  
  <p>Where the longitude/latitude are way off.</p>
  
  <p>I've tried manually setting the <code>Point</code> to the location:</p>
  
  <pre><code>obj.point = Point(-94.577597, 39.057294)
  obj.save()
  </code></pre>
  
  <p>but the widget is then rendered way off.</p>
  
  <p>So it seems that the wrong latitude and longitude are being saved to the field, or the wrong coordinate system is being used.</p>
  
  <p>I've tried to manually override the widget to make sure the correct SRID is being used on the widget with:</p>
  
  <pre><code>class Meta:
      model = models.MyModel
      fields = "__all__"
      widgets = {
          'point': widgets.OSMWidget(attrs={
              'map_srid': 4326,
              'map_width': 800,
              'map_height': 500,
              'display_raw': True
          })
      }
  </code></pre>
  
  <p>but no luck.</p>
  
  <p>I have all the dependencies for GeoDjango installed, I've enabled the postgis extension on my database and I the correct engine in use:</p>
  
  <pre><code>DATABASES['default']['ENGINE'] = 'django.contrib.gis.db.backends.postgis'
  </code></pre>
  
  <p>I also have added <code>django.contrib.gis</code> to <code>INSTALLED_APPS</code>. I'm using the default form widget, but I'm wondering might the widget be the problem?</p>