Removed u, d and s format specifiers

See:
rust-lang/rust#19040
https://github.com/rust-lang/rfcs/blob/master/text/0380-stabilize-std-fmt.md

Author: abspoel

src/reply.rs

@@ -150,7 +150,7 @@ impl<T: Copy> ReplyRaw<T> {
 impl<T: Copy> Drop for ReplyRaw<T> {
     fn drop (&mut self) {
         if self.sender.is_some() {
-            warn!("Reply not sent for operation {:u}, replying with I/O error", self.unique);
+            warn!("Reply not sent for operation {}, replying with I/O error", self.unique);
             self.send(EIO, []);
         }
     }