title: InvalidConfigurationException: The child node "key" at path "security.firewalls.main.remember_me" must be configured
body: <p>I tried to update my vendor bundles in symfony2 using php composer.phar update, but when I did so I received an error after this line: </p>
  
  <p>Updating the "app/config/parameters.yml" file</p>
  
  <p>The error I get is:</p>
  
  <pre><code>[Symfony\Component\Config\Definition\Exception\InvalidConfigurationException]           
  The child node "key" at path "security.firewalls.main.remember_me" must be configured. 
  
  Script Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache handling the post-update-cmd event terminated with an exception
  
  [RuntimeException]                                                         
  An error occurred when executing the "'cache:clear --no-warmup'" command. 
  </code></pre>
  
  <p>My security.yml file has the following in its firewall section:</p>
  
  <pre><code>firewalls:
      main:
          pattern: ^/
          provider: fos_userbundle
          form_login:
              csrf_provider: form.csrf_provider
              always_use_default_target_path: false
              default_target_path: webplio_site_dashboard_index
              #success_handler: webplio_site.login_success_handler
              check_path: /login_check
              login_path: /login
          logout: true
          remember_me: true
          anonymous: true
          remember_me:
              key: "%secret%"
              lifetime: 31536000 # 365 days in seconds
              path: /
              domain: ~ # Defaults to the current domain from $_SERVER
  </code></pre>
  
  <p>where secret is defined in my parameters.yml file</p>
  
  <p>My question then is what else do I need to do in order to configure the child node "key" at path "security.firewalls.main.remember_me"?</p>