message: add command to build client for deployment and point to the heroku server
diff: "start": "ng serve",
  "startHeroku": "ng serve --environment=dev-heroku",
  "build": "ng build",
  + "buildHeroku": "ng build --environment=dev-heroku",
  "test": "ng test",
  "lint": "ng lint",
  "e2e": "ng e2e"
  