Fix stream use

Author: sfackler

test.rs

@@ -45,7 +45,7 @@ fn test_pool() {
     let pool = PostgresConnectionPool::new("postgres://postgres@localhost",
                                            NoSsl, 2);
 
-    let (stream1, stream2) = DuplexStream::<(), ()>();
+    let (stream1, stream2) = DuplexStream::<(), ()>::new();
 
     let pool1 = pool.clone();
     let mut fut1 = do Future::spawn {