title: Utilising composers asset-installer-paths not working
body: <p>I'm trying to install a certain package in composer into a certain path, the package name is <code>cyphix333/nbbc</code> and normally it would be installed into <code>vendor/cyphix333/nbbc</code> however I wanted to install it into <code>vendor/nbbc</code> so I tried this in the main project <code>composer.json</code></p>
  
  <pre><code>"require": {
      //......
      "cyphix333/nbbc": "dev-master"
  },
  
  "extra": {
      "asset-installer-paths": {
          //.....
          "cyphix333/nbbc": "vendor/nbbc"
      }
  }
  </code></pre>
  
  <p>However it didn't work, it still installed into <code>vendor/cyphix333/nbbc</code>.</p>
  
  <p><strong>Edit:</strong> ...and here is the full data from the <code>extra</code> part, which comes from my php framework <code>yii2</code>:</p>
  
  <pre><code>"extra": {
      "yii\\composer\\Installer::postCreateProject": {
          "setPermission": [
              {
                  "runtime": "0777",
                  "web/assets": "0777",
                  "yii": "0755"
              }
          ],
          "generateCookieValidationKey": [
              "config/web.php"
          ]
      },
      "asset-installer-paths": {
          "npm-asset-library": "vendor/npm",
          "bower-asset-library": "vendor/bower",
          "cyphix333/nbbc": "vendor/nbbc"
      }
  }
  </code></pre>
  
  <p>What am I doing wrong here?</p>