Update features and deprecated items

examples/extract.rs

@@ -1,4 +1,4 @@
-#![feature(path, io, fs, exit_status)]
+#![feature(path, io, exit_status)]
 
 extern crate zip;
 

examples/extract_lorem.rs

@@ -1,4 +1,4 @@
-#![feature(path, io, fs, exit_status)]
+#![feature(path, io, exit_status)]
 
 use std::io::prelude::*;
 

examples/write_sample.rs

@@ -1,4 +1,4 @@
-#![feature(io, fs, path, exit_status)]
+#![feature(io, path, exit_status)]
 
 use std::io::prelude::*;
 

src/result.rs

@@ -26,7 +26,7 @@ pub enum ZipError
 
 impl ZipError
 {
-    fn detail(&self) -> ::std::string::CowString
+    fn detail(&self) -> ::std::borrow::Cow<str>
     {
         use ::std::error::Error;
         use ::std::borrow::IntoCow;