fix(rustup): update io import, Writer::write

Make it build with the latest rust-nightly (2015-01-27)

Renamed io import to old_io.
Renamed Writer::write to Writer::write_all

src/client/request.rs

@@ -1,5 +1,5 @@
 //! Client Requests
-use std::io::{BufferedWriter, IoResult};
+use std::old_io::{BufferedWriter, IoResult};
 
 use url::Url;
 
@@ -157,8 +157,8 @@ impl Request<Streaming> {
 
 impl Writer for Request<Streaming> {
     #[inline]
-    fn write(&mut self, msg: &[u8]) -> IoResult<()> {
-        self.body.write(msg)
+    fn write_all(&mut self, msg: &[u8]) -> IoResult<()> {
+        self.body.write_all(msg)
     }
 
     #[inline]