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/header/common/allow.rs

@@ -1,6 +1,6 @@
 use header::{Header, HeaderFormat};
 use method::Method;
-use std::fmt::{mod};
+use std::fmt::{self};
 use header::shared::util::{from_comma_delimited, fmt_comma_delimited};
 
 /// The `Allow` header.
@@ -31,7 +31,7 @@ impl HeaderFormat for Allow {
 mod tests {
     use super::Allow;
     use header::Header;
-    use method::Method::{mod, Options, Get, Put, Post, Delete, Head, Trace, Connect, Patch, Extension};
+    use method::Method::{self, Options, Get, Put, Post, Delete, Head, Trace, Connect, Patch, Extension};
 
     #[test]
     fn test_allow() {