Merge pull request #452 from isaacs/master

nopt: allow version 3
Making Chromium's gyp more apparent in the README.
Merge pull request #457 from jsdevel/master

Making Chromium's gyp more apparent in the README.
use sha256 checksums starting with node v0.10.0
Merge pull request #459 from freewil/sha256

use sha256 checksums starting with node v0.10.0
allow semver@3