title: Error about compass when trying to run 'assetic:dump'
body: <p>I'm getting the error below when i try to run : <code>php app/console assetic:dump --env=dev --no-debug</code>.</p>
  
  <p>I don't know if it is related or not.</p>
  
  <pre><code>[Assetic\Exception\FilterException]                                                                                  
    An error occurred while running:                                                                                     
    '/usr/bin/ruby' '/usr/local/bin/compass' 'compile' '/tmp' '--images-dir' '/home/tirengarfio/workspace/canalones/app  
    /../web/images' '--config' '/tmp/assetic_compassYNg6JH' '--sass-dir' '' '--css-dir' '' '/tmp/assetic_compasssdSsQF.  
    scss'                                                                                                                
  
    Error Output:                                                                                                        
    /usr/lib/ruby/1.9.1/rubygems/dependency.rb:247:in `to_specs': Could not find compass (&gt;= 0) amongst [sass-3.2.5] (G  
    em::LoadError)                                                                                                       
      from /usr/lib/ruby/1.9.1/rubygems/dependency.rb:256:in `to_spec'                                                    
      from /usr/lib/ruby/1.9.1/rubygems.rb:1231:in `gem'                                                                  
      from /usr/local/bin/compass:18:in `&lt;main&gt;'                                                                          
  
  
    Input:                                                                                                               
    @import "compass/css3";                                                                                              
    @import "compass/utilities";                                                                                         
  
    $naranja: #FF6600;                                                                                                   
    $blanco: #FFFFFF;                                                                                                    
    $verde_oscuro: #006666;                                                                                              
    $verde_claro: #009900;                                                                                               
  
    #content_center {                                                                                                    
    position: relative;                                                                                                  
        #bg {                                                                                                            
            /*background: url('/bundles/canalonesfrontend/images/bg_gris_puntos.png');*/                                 
            background: url('/bundles/canalonesfrontend/images/otis_redding.png');                                       
            width: 800px;                                                                                                
            height: 330px;                                                                                               
            position: absolute;                                                                                          
        }                                                                                                                
        .slides_container {                                                                                              
            width:570px;                                                                                                 
            height:270px;                                                                                                
            margin: 0 auto;                                                                                              
            position: absolute;                                                                                          
            z-index: 10;                                                                                                 
            div {                                                                                                        
            margin-top: 25px;                                                                                            
               width:570px;                                                                                              
               height:270px;                                                                                             
               display:block;                                                                                            
           }                                                                                                             
        }                                                                                                                
    }                                                                                                                    
  
  
    #container_info                                                                                                      
    {                                                                                                                    
       .item_info {                                                                                                      
           background: $naranja;                                                                                         
           width: 192px;                                                                                                 
           height: 250px;                                                                                                
           float: left;                                                                                                  
           margin: 15px;                                                                                                 
           padding: 10px 19px;                                                                                           
           border: 3px solid orange;                                                                                     
           @include border-radius(14px);                                                                                 
           .title {                                                                                                      
               color: $blanco;                                                                                           
               margin: 9px 0;                                                                                            
           }                                                                                                             
           .content {                                                                                                    
           }                                                                                                             
       }                                                                                                                 
    }       
  </code></pre>
  
  <p>NOTE: one guy is having <a href="http://alexandre-salome.fr/blog/Sass-Compass-Assetic-In-Ten-Minutes" rel="nofollow">here</a> the same problem some time ago, and other person replies that he should make compass work as standalone, but.. any idea how?                                      </p>