Remove future re-exports (#133)

These types were moved around in
https://github.com/tokio-rs/axum/pull/130 but re-export from their old
location for backwards compatibility.

This removes the re-exports.

src/service/mod.rs

@@ -89,7 +89,7 @@
 use crate::{
     body::BoxBody,
     response::IntoResponse,
-    routing::{EmptyRouter, MethodFilter, RouteFuture},
+    routing::{future::RouteFuture, EmptyRouter, MethodFilter},
 };
 use bytes::Bytes;
 use http::{Request, Response};
@@ -103,10 +103,6 @@ use tower::{util::Oneshot, BoxError, Service, ServiceExt as _};
 
 pub mod future;
 
-// for backwards compatibility
-#[doc(hidden)]
-pub use future::BoxResponseBodyFuture;
-
 /// Route requests to the given service regardless of the HTTP method.
 ///
 /// See [`get`] for an example.