title: Symfony2 assetic:dump wrong write_to path
body: <p>I have a longtime problem with assetic:dump. I wanna use "assetic" to get Javascript and CSS files from different bundles (I wrote) and collect them to dev and prod environment in the templates. Everytime I wanna dump new files, the assetic:dump command try to write in a complete broken path.</p>
  
  <pre><code>app/console assetic:dump
  
    [RuntimeException]                                                                                       
    Unable to create directory /var/www/app/../web//var/www/app/../htdocs/css  
  </code></pre>
  
  <p>I also try writing in: (nothing works)</p>
  
  <pre><code>app/console assetic:dump web
  app/console assetic:dump .
  app/console assetic:dump /var/www/web
  </code></pre>
  
  <p>I configured assetic like this:</p>
  
  <pre><code>assetic:
      debug:          %kernel.debug%
      use_controller: false
      read_from: "%kernel.root_dir%/../web"
      write_to: "%kernel.root_dir%/../web"
      bundles:
        - MyCodeBundle
        - NextCodeBundle
      #java: /usr/bin/java
      filters:
          lessphp:
              file: %kernel.root_dir%/../vendor/oyejorge/less.php/lessc.inc.php
              apply_to: "\.less$"
          cssrewrite: ~
  </code></pre>
  
  <p>I use also <em>BraincraftedBootstrapBundle</em> to use Twitter Bootstrap Js/CSS in my templates.</p>
  
  <p>Where I can fix the path of assetic:dump?</p>