title: laravel 5.2: Command "optimize" is not defined
body: <p>I am working on laravel 5.2.</p>
  
  <p>When I run composer install and composer update command, it show error:</p>
  
  <pre><code>[InvalidArgumentException] Command "optimize" is not defined.
  </code></pre>
  
  <p>Please let me know how to solved this problem.</p>