Update for latest rust

Tracks rust nightly.

7 tests fail -- still finding source

src/status.rs

@@ -1585,13 +1585,19 @@ impl Copy for StatusCode {}
 /// ```
 ///
 /// If you wish to just include the number, cast to a u16 instead.
-impl fmt::Show for StatusCode {
+impl fmt::String for StatusCode {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{} {}", *self as u16,
                self.canonical_reason().unwrap_or("<unknown status code>"))
     }
 }
 
+impl fmt::Show for StatusCode {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        self.to_string().fmt(fmt)
+    }
+}
+
 // Specified manually because the codegen for derived is slow (at the time of writing on the machine
 // of writing, 1.2 seconds) and verbose (though the optimiser cuts it down to size).
 impl PartialEq for StatusCode {