Remove note about AsyncBufRead (#68)

src/connection.rs

@@ -24,10 +24,7 @@ pub struct Connection {
     // sufficient for our needs.
     stream: BufWriter<TcpStream>,
 
-    // The buffer for reading frames. Unfortunately, Tokio's `BufReader`
-    // currently requires you to empty its buffer before you can ask it to
-    // retrieve more data from the underlying stream, so we have to manually
-    // implement buffering. This should be fixed in Tokio v0.3.
+    // The buffer for reading frames.
     buffer: BytesMut,
 }