title: CloseNotifier for http ResponseWriter
body: <p>i am using go 1.4.2 and the implementation doesn't seem to have <code>CloseNotifier</code> as i want to use it in a long polling handler with something like:</p>
  
  <pre><code>func Pollhandler(w http.ResponseWriter, r *http.Request) {
  
      notify := w.(CloseNotifier).CloseNotify()
  
      &lt;-notify //should block until the http connection is closed
  
  }
  </code></pre>
  
  <p>is the CloseNotifier not implemented for the http <code>ResponseWriter</code>? if so how can i get around this? or is there any implementation for http <code>ResponseWriter</code> that implements the <code>CloseNotifier</code> interface?</p>