Removed 'Initializer' import and use as it seems to not exist anymore

This was causing compilation issues which are now fixed for me

quinn/src/streams.rs

@@ -5,7 +5,7 @@ use std::str;
 use bytes::Bytes;
 use err_derive::Error;
 use futures::channel::oneshot;
-use futures::io::{AsyncRead, AsyncWrite, Initializer};
+use futures::io::{AsyncRead, AsyncWrite};
 use futures::task::Context;
 use futures::{ready, Future, FutureExt, Poll};
 use proto::{ConnectionError, StreamId};
@@ -421,10 +421,6 @@ impl AsyncRead for RecvStream {
             },
         ))
     }
-
-    unsafe fn initializer(&self) -> Initializer {
-        Initializer::nop()
-    }
 }
 
 impl tokio_io::AsyncRead for RecvStream {