title: AFNetworking+UIImageView placeholder image shows up, but not URL image
body: <p>I'm trying to use the AFNetworking UIImageView call to load images from a URL as shown below:</p>
  
  <pre><code>[self.image setImageWithURL:[NSURL URLWithString:feed.imageURL] placeholderImage:     [UIImage imageNamed:@"logo"]];
  </code></pre>
  
  <p>The placeholder image always shows up, but the actual image from "feed.imageURL" never does. I've verified that the URL is actually correct.  I even hardcoded it to make sure, and still nothing.</p>
  
  <p>My basic app setup is a tab controller...and in viewDidLoad, I call a method "fetchFeed" which performs the HTTP request to gather my JSON data.</p>
  
  <p>My request block looks like:</p>
  
  <pre><code>AFJSONRequestOperation *operation = [AFJSONRequestOperation
                                      JSONRequestOperationWithRequest:request
                                       success:^(NSURLRequest *request, NSHTTPURLResponse   *response, id JSON) {
                                           [self parseDictionary:JSON];
                                           isLoading = NO;
                                           [self.tableView reloadData];
  
                                           } failure:^(NSURLRequest *request,   NSHTTPURLResponse *response, NSError *error, id JSON) {
                                               NSLog(@"Error: %@", error);
                                               [self showNetworkError];
                                               isLoading = NO;
                                               [self.tableView reloadData];
                                           }];
  operation.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html", nil];
  [queue addOperation:operation];
  </code></pre>