如何安装magento2

Question

有没有办法使用composer安装magento2？我找到了一个命令

 composer create-project magento/community-edition ./ -s dev --prefer-dist

但是只有一个composer.json然后

才能实现

 composer install 

？我试过这个：

{
  "name": "asfasf",
  "require": {
    "magento/magento-composer-installer": "*",
    "magento/product-community-edition": "0.1.0-alpha89"
  },
  "repositories": [
    {
      "type": "composer",
      "url": "http://packages.magento.com/"
    }
  ],
  "extra": {
    "magento-root-dir": "htdocs",
    "magento-deploystrategy": "copy"
  },
  "minimum-stability": "dev"
}

但是会抛出错误

[Composer\Downloader\TransportException]                                      
Your configuration does not allow connections to http://packages.magento.com/packages.json. 

我做错了什么提示？