Heroku push master命令为node.js项目提供错误

Question

请查看附件以查看使用Heroku文档部署node.js项目时出现的错误。 它给了我这个错误： 节点版本未指定。 这是我的package.json文件：

{
  "name": "Main",
  "version": "1.0.0",
  "description": "Main",
  "main": "app.js",
  "author": {
  "name": "Umeriftikhar",
  "email": ""
},
"dependencies": {
"express": "3.4.4",
 "jade": "*",
"stylus": "*",
"ejs" : "~0.8.5",               
"mongoose" : "~3.8.1",          
"passport" : "~0.1.17",         
"passport-local" : "~0.1.6",    
"passport-facebook" : "~1.0.2", 
"passport-twitter" : "~1.0.2",  
"passport-google-oauth" : "~0.1.5",
"connect-flash" : "~0.1.1",     
"bcrypt-nodejs" : "latest",

"morgan": "~1.0.0",
"body-parser": "~1.0.0",
"cookie-parser": "~1.0.0",
"method-override": "~1.0.0",
"express-session": "~1.0.0" 
 },
 "engines": {
 "node": "4.2.1",
  "npm": "2.14.7"
 },
"repository": {
"type": "git",
"url": "https://github.com/UmerIftikhar/Server.git"
 }
}