message: add a clean script to remove cli pkg artifacts
diff: "pub": "yarn pkg && npm-run-all pub:*",
  "pub:tarball": "aws s3 cp ./dist/cardpay.tgz s3://cardpay-install",
  "pub:installer": "aws s3 cp ./bin/install-cardpay.sh s3://cardpay-install",
  - "pub:invalidate": "aws cloudfront create-invalidation --distribution-id ETWZIWCWU250B --paths \"/cardpay.tgz\" \"/install-cardpay.sh\" > /dev/null"
  + "pub:invalidate": "aws cloudfront create-invalidation --distribution-id ETWZIWCWU250B --paths \"/cardpay.tgz\" \"/install-cardpay.sh\" > /dev/null",
  + "pub:clean":"rm -rf ./dist"
  },
  "bin": {
  "cardpay": "./cardpay.js"
  