Expo deployment through wercker

wercker.yml

box: node
build:
  steps:
    - script:
      name: Install Exponent CLI
      code: |
        npm install -g exp

    # A step that executes `npm install` command
    - npm-install

    # Steps to run the deployment
    - script:
      name: Log-in to exponent account
      code: |
        exp login -u $EXPO_USERNAME -p $EXPO_PASSWORD

    - script:
      name: Publish the application
      code: |
        exp publish