ReactiveCocoa/ReactiveCocoa — pull request #1466 by kiennt (2014-08-15 14:45:14+00:00)
Title: Support UIBarButtonItem with UIButton customView

In my application, I need to set up `rac_command` for UIBarButtonItem

```objC
UIImage *backImage = [UIImage imageNamed:@"back-arrow-button.png"];
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setImage:backImage forState:UIControlStateNormal];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:button];

self.navigationItem.leftBarButtonItem.rac_command = [[RACCommand alloc] initWithSignalBlock:^RACSignal *(id input) {
return [RACSignal createSignal:^RACDisposable *(id subscriber) {
// do some thing in here
return nil;
}];
}];
```

But since UIBarButtonItem with customView does not support set `target` and `action`, so I need to make a new variable of class to store `self.button`

This fix will resolve this issue