Utilize fewer reexports

In regards to:

https://github.com/rust-lang/rust/issues/19253#issuecomment-64836729

This commit:

* Changes the #deriving code so that it generates code that utilizes fewer
  reexports (in particur Option::* and Result::*), which is necessary to
  remove those reexports in the future
* Changes other areas of the codebase so that fewer reexports are utilized

src/libstd/error.rs

@@ -78,7 +78,8 @@
 //! }
 //! ```
 
-use option::{Option, None};
+use option::Option;
+use option::Option::None;
 use kinds::Send;
 use string::String;