feat(net): add socket timeouts to Server and Client

While these methods are marked unstable in libstd, this is behind a
feature flag, `timeouts`. The Client and Server both have
`set_read_timeout` and `set_write_timeout` methods, that will affect all
connections with that entity.

BREAKING CHANGE: Any custom implementation of NetworkStream must now
  implement `set_read_timeout` and `set_write_timeout`, so those will
  break. Most users who only use the provided streams should work with
  no changes needed.

Closes #315

src/client/pool.rs

@@ -5,6 +5,9 @@ use std::io::{self, Read, Write};
 use std::net::{SocketAddr, Shutdown};
 use std::sync::{Arc, Mutex};
 
+#[cfg(feature = "timeouts")]
+use std::time::Duration;
+
 use net::{NetworkConnector, NetworkStream, DefaultConnector};
 
 /// The `NetworkConnector` that behaves as a connection pool used by hyper's `Client`.
@@ -153,6 +156,18 @@ impl<S: NetworkStream> NetworkStream for PooledStream<S> {
         self.inner.as_mut().unwrap().1.peer_addr()
     }
 
+    #[cfg(feature = "timeouts")]
+    #[inline]
+    fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
+        self.inner.as_ref().unwrap().1.set_read_timeout(dur)
+    }
+
+    #[cfg(feature = "timeouts")]
+    #[inline]
+    fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
+        self.inner.as_ref().unwrap().1.set_write_timeout(dur)
+    }
+
     #[inline]
     fn close(&mut self, how: Shutdown) -> io::Result<()> {
         self.is_closed = true;