Fix composer installation

[murich]

 composer install
Loading composer repositories with package information
Installing dependencies (including require-dev)                        
  - Installing joshuaestes/composer-installer-puppet (2.0.0)
    Cloning ac30dc53eb4afa5714555ace62c22415048b892c

PHP Fatal error:  Class 'JoshuaEstes\Composer\Installer\PuppetPlugin' not found in phar:///usr/local/bin/composer/src/Composer/Plugin/PluginManager.php on line 234

Fatal error: Class 'JoshuaEstes\Composer\Installer\PuppetPlugin' not found in phar:///usr/local/bin/composer/src/Composer/Plugin/PluginManager.php on line 234