title: White screen of death when including Elastica Bundle
body: <p>I'm trying to add the Elasticsearch bundle to my symfony2 project, when I add the bundle </p>
  
  <pre><code>// app/AppKernel.php
  
  public function registerBundles()
  {
      $bundles = array(
          // ...
          new FOS\ElasticaBundle\FOSElasticaBundle(),
      );
  }
  </code></pre>
  
  <p>1st case : I don't touch the config file: Result : White screen of death
  I put some configuration</p>
  
  <pre><code>fos_elastica:
  clients:
      default: { host: localhost, port: 9200 }
  indexes:
      website:
          client: default
          types:
              user:
                  mappings:
                      coordinates: { boost: 5 }
  </code></pre>
  
  <p>Results : White screen of death! 
  Does anyone have any idea about what's going on ? </p>