src,test,tools: modify for more stringent linting

ESLint 2.1.0 is coming. Some lint rules have been tightened.

PR-URL: https://github.com/nodejs/node/pull/5214


Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: jbergstroem - Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Myles Borins <myles.borins@gmail.com>