cross-ci/bin/cross-ci.js

`cross-ci` standardizes environment variables for CI. For example, your can simply use `BUILD_BRANCH` variable in all CI runners instead of `CIRCLE_BRANCH` in CircleCI or `TRAVIS_PULL_REQUEST_BRANCH` in Travis.

#!/usr/bin/env node

// eslint-disable-next-line import/no-unassigned-import
require("../lib/cli");