title: Not animation on item removed in UICollectionView with RxDataSources
body: <p>After following the <a href="https://github.com/RxSwiftCommunity/RxDataSources" rel="nofollow noreferrer">Documentation</a> of <em>RxDataSources</em> I'm not able to make it work.</p>
  <p>When I click on an element of the CollectionViews It is removed as my code shows but nothing happens on the views, despite there is an element less on my <code>sections[0].items</code>. I reckon that I'm doing some wrong binding the data source with the view but I'm not able to figure it out.</p>
  <pre><code>    let dataSource = RxCollectionViewSectionedAnimatedDataSource&lt;SectionOfCategoryMO&gt;()
      private var e1cat = CatMngr.SI.getAlphabeticallyOrderedCategories(type: .e1)
  
      dataSource.configureCell = { ds, tv, ip, item in
          let cell = tv.dequeueReusableCellWithReuseIdentifier(&quot;cell&quot;, forIndexPath: ip) as! CategoryCollectionViewCell
          cell.categoryName.text = item.identity.string
          cell.categoryName.numberOfLines = 0
          cell.categoryCircle.makeCircle()
          cell.categoryCircle.backgroundColor = self.categoryColors[ip.row]
          
          return cell
      }
      
      dataSource.animationConfiguration = AnimationConfiguration(insertAnimation: .Fade, reloadAnimation: .Fade, deleteAnimation: .Automatic)
      
      var sections = [SectionOfCategoryMO(header: &quot;a&quot;, items: e1cat)]
      
      Observable.just(sections)
          .bindTo(myCollection.rx_itemsWithDataSource(dataSource))
          .addDisposableTo(disposeBag)
   
      myCollection.rx_itemSelected.subscribeNext{
          sections[0].items.removeAtIndex($0.row)
      }.addDisposableTo(disposeBag)
  </code></pre>
  <p>The view is loaded perfectly with all initial categories, but when I remove one of them the view is not refreshed.</p>
  <p>Anyone know what is happening?</p>
  <p>Thanks in advance.</p>