cross-ci/lib/var/RELEASE_BRANCHES.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.

/// Names of branches which should trigger a release,
/// defaults to `['master', 'production']`.
const RELEASE_BRANCHES = () => ['master', 'production'];

module.exports = RELEASE_BRANCHES;