add SendResponse::poll_reset and SendStream::poll_reset to listen for reset streams (#279)

src/share.rs

@@ -319,6 +319,22 @@ impl<B: IntoBuf> SendStream<B> {
     pub fn send_reset(&mut self, reason: Reason) {
         self.inner.send_reset(reason)
     }
+
+    /// Polls to be notified when the client resets this stream.
+    ///
+    /// If stream is still open, this returns `Ok(Async::NotReady)`, and
+    /// registers the task to be notified if a `RST_STREAM` is received.
+    ///
+    /// If a `RST_STREAM` frame is received for this stream, calling this
+    /// method will yield the `Reason` for the reset.
+    ///
+    /// # Error
+    ///
+    /// If connection sees an error, this returns that error instead of a
+    /// `Reason`.
+    pub fn poll_reset(&mut self) -> Poll<Reason, ::Error> {
+        self.inner.poll_reset(proto::PollReset::Streaming)
+    }
 }
 
 // ===== impl RecvStream =====