title: Fatal error on executing custom console command in symfony
body: <p>I'm trying to create a custom console command for my project so i thought I'll first try it out with the example given in the symfony site, I have provided the steps it took to reach this far,</p>
  
  <pre><code>Step 1: Added  "symfony/console": "2.3.*@dev", to composer.json.
  Step 2: Updated composer.
  </code></pre>
  
  <p>The code written for the command is given below</p>
  
  <pre><code>class Sendgcmfuctions extends ContainerAwareCommand {
  protected function configure()
  {
      $this
          -&gt;setName('demo:greet')
          -&gt;setDescription('Greet someone')
          -&gt;addArgument('name', InputArgument::OPTIONAL, 'Who do you want to greet?')
          -&gt;addOption('yell', null, InputOption::VALUE_NONE, 'If set, the task will yell in uppercase letters')
      ;
  }
  
  protected function execute(InputInterface $input, OutputInterface $output)
  {
      $name = $input-&gt;getArgument('name');
      if ($name) {
          $text = 'Hello '.$name;
      } else {
          $text = 'Hello';
      }
  
      if ($input-&gt;getOption('yell')) {
          $text = strtoupper($text);
      }
  
      $output-&gt;writeln($text);
  }
  }
  </code></pre>
  
  <p>On running "php app/console demo:greet" the following error is produced</p>
  
  <pre><code>PHP Fatal error:  Class 'Doctrine\ORM\Tools\Console\Command\ClearCache\QueryRegionCommand' not found in /var/www/MobpazAdmin/vendor/doctrine/doctrine-bundle/Doctrine/Bundle/DoctrineBundle/Command/Proxy/QueryRegionCacheDoctrineCommand.php on line 29
  </code></pre>
  
  <p>The "Sendgcmfuctions" is inside a Command folder inside my bundle. Please tell me the mistake commited while doing this</p>