cross-ci/lib/var/UPLOAD_PATH.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.

/// Relative upload path for artifacts. Defaults to:
///
/// ```
/// builds/${PROJECT_NAME}/${BUILD_VERSION}
/// ```
const UPLOAD_PATH = ({PROJECT_NAME, BUILD_VERSION}) =>
    process.env.UPLOAD_PATH
    || `builds/${PROJECT_NAME}/${BUILD_VERSION}`;

module.exports = UPLOAD_PATH;