More Rust updates:

- Some stray deriving -> derive changes
- use::{mod} -> use::{self}
- fmt.write -> fmt.write_str

This does not catch the last case of fmt.write_str in the
Show impl of a Header Item. This will need to be changed
separately.

src/status.rs

@@ -1,7 +1,10 @@
 //! Status Codes
 use std::fmt;
+use std::num::{FromPrimitive, ToPrimitive};
 use std::mem::transmute;
 
+use std::cmp::Ordering::{self, Less, Equal, Greater};
+
 // shamelessly lifted from Teepee. I tried a few schemes, this really
 // does seem like the best.