title: RxSwift using bindTo for binding Variable<String> to UILabel not working for Swift 3.0 update
body: <p>I use <code>RxSwift</code> to bind my <code>viewmodel</code> to <code>UILabel</code> and <code>UITexfield</code>. <code>UITextfield</code> ones have no issues converting to <code>Swift 3</code>, just replacing <code>rx_text</code> with <code>rx.text</code> worked. </p>
  
  <p>But not for <code>UILabel</code>. On <code>Swift 2.2</code>, I used:</p>
  
  <pre><code>self.viewModel.shiftNameText.asObservable().bindTo(self.shiftLabel.rx_text).addDisposableTo(self.disposeBag)
  </code></pre>
  
  <p>For <code>Swift 3</code>, I'm using <code>RxSwift</code> 3.0.0-beta.1 and tried just changing rx_text to <strong>rx.text</strong>, but it doesn't compile and shows this error "Cannot convert value of type '<code>AnyObserver&lt;String?&gt;' (aka 'AnyObserver&lt;Optional&lt;String&gt;&gt;') to expected argument type 'Variable&lt;String&gt;".</code></p>
  
  <p>Does anyone know why and how to make this work? Thanks.</p>