title: Django-tastypie pass request.user to custom save method
body: <p>Since my model's custom save method takes request.user as an argument I'm unable to do POST/PUT requests. </p>
  
  <pre><code>TypeError at /api/obsadmin/observation/23
  save() takes at least 2 arguments (1 given)
  </code></pre>
  
  <p>I'm using SessionAuthentication() and have included the CSRF token. </p>
  
  <p>Here's the relevant model part:</p>
  
  <pre><code>def save(self, user, owner=None, *args, **kwargs):
      self.updated_by = user.id
      super(ObsModel, self).save(*args, **kwargs)
  </code></pre>
  
  <p>And the resource:</p>
  
  <pre><code>class ObservationResource2(ModelResource):
  
  comments = fields.ToManyField(CommentResource2, 'comments', full=True, null=True)
  
  class Meta:
      queryset = Observation.objects.filter(is_verified=True)
      authentication = SessionAuthentication()
      authorization = DjangoAuthorization()
      resource_name = 'observation'
      always_return_data = True
  </code></pre>