title: STL file read using three.js issue
body: <p>I am able to read successfully stl file by three.js but problem is that is not showing exact color which is defined in the stl file. My code looks like:</p>
  
  <pre><code>var loader = new THREE.STLLoader();
  loader.addEventListener( 'load', function ( event ) {
      var geometry = event.content;
      var material = new THREE.MeshPhongMaterial( { ambient: 0x555555, color: 0xAAAAAA, specular: 0x111111, shininess: 200 } );
      if (geometry.hasColors) {
          material = new THREE.MeshPhongMaterial({ color: 0xFFFFFF, specular: 0x111111, ambient: 0x555555, opacity: geometry.alpha, vertexColors: THREE.VertexColors });
      }
      var mesh = new THREE.Mesh( geometry, material );
      mesh.position.x = x - w/2;
      mesh.position.y = y;
      mesh.position.z = - h + h/2 + z/2;
      //mesh.rotation.set( 0.5, 0, 0 );
      mesh.castShadow = true;
      mesh.receiveShadow = true;
      board.add(mesh);
  } );
  
  loader.load( fileName ); 
  </code></pre>
  
  <p>But its showing only black color after applying vertex color.
  Any suggestion?</p>