title: Symfony 2 no command for generating doctrine crud
body: <p>i`m trying to generate CRUD for some entities in Symfony 2, apparently the 
  generate:doctrine:crud command is unavailable.</p>
  
  <pre><code>  [InvalidArgumentException]                        
    Command "generate:doctrine:crud" is not defined.  
  </code></pre>
  
  <p>also , in the list for available commands, I only get one command.</p>
  
  <pre><code>generate
    generate:doctrine:entities            Generates entity classes and method stubs from your mapping information
  </code></pre>
  
  <p>is there a bundle or something in the configuration missing, or what is the cause for not having this functionality.</p>