define build process for deploying to npm

[ckundo]

Open questions:

• Do we have a release branch with the build artifacts?
• When/where do we deploy to npm registry? Locally? From CI?

@addyosmani you've been managing the a11y node module I believe. Any thoughts or recommendations based on your experience? cc @alice

[jessebeach]

Up to this point I've run these two commands to release to NPM:

1. npm version patch
2. npm publish

I've never worked on an NPM project with multiple authors. Do we just add usernames to the package.json so other folks can publish to the package endpoint as well?

Also, @ckundo I'm just relying on npm publish to create the lib/ dir in the package straight off the master branch. My preference is to avoid complex release models i.e. with a release branch. All work goes right into master; we use semver to and npm version to indicate release milestones.