Pin `npm-shrinkwrap` to `5.0.0` to support `npm@2.x`

Fixes #180.
Refs https://github.com/uber/npm-shrinkwrap/issues/51#issuecomment-62684260
E034: Fix firing when `.close` button is not preceded by anything

Fixes #181.
Mention bootlint.com in the README

Closes #173.
CLI: Add support for linting stdin input
Usage instructions for linting stdin in README