title: How to add private github repository as Composer dependency
body: <p>I have the following in my Laravel 5.1 projects composer.json to add a public github repository as a dependency.</p>
  
  <pre><code>...    
  "repositories": [
    {
      "type": "package",
      "package": {
        "name": "myVendorName/my_private_repo",
        "version": "1.2.3",
        "source": {
          "type" : "git",
          "url" : "git://github.com/myVendorName/my_private_repo.git",
          "reference" : "master"
        },
        "dist": {
          "url": "https://github.com/myVendorName/my_private_repo/archive/master.zip",
          "type": "zip"
        }
      }
    }
  ],
  "require": {
       ....
      "myVendorName/my_private_repo": "*",
  },
  ...
  </code></pre>
  
  <p>This works as long as the repository is public. Now I've set this repository to private. The git credentials I use for pulling/pushing to 'my_private_repo' are the one of a colaborator of the project. How can I achieve that composer pulls from that private repository when I run <strong>composer update</strong> or <strong>composer install</strong>?</p>