added heroku scripts into package.json

Author: jazibsawar

package.json

@@ -7,8 +7,7 @@
  "scripts": {
  "dev": "node build/dev-server.js",
  "start": "node server.js",
- "heroku-prebuild": "export NPM_CONFIG_PRODUCTION=false; export NODE_ENV=; NPM_CONFIG_PRODUCTION=false NODE_ENV=development npm install",
- "heroku-postbuild": "export NPM_CONFIG_PRODUCTION=true; export NODE_ENV=production;",
+ "heroku-prebuild": "npm install",
  "build": "node build/build.js",
  "postinstall": "npm run build",
  "lint": "eslint --ext .js,.vue src"