Laravel5.0.x の Elixir3.0.x で compass を使う

var gulp = require('gulp');
var compass = require('gulp-compass');
var Elixir = require('laravel-elixir');
var Task = Elixir.Task;

var compassTask = function(src, output, options) {
    new Elixir.Task('compass', function() {
        return (gulp.src(src).pipe(compass(options)).pipe(gulp.dest(output)));
    }).watch(config.get('assets.css.sass.folder') + '/**/*.+(sass|scss)');
};
Elixir.extend('compass', function() {
    compassTask.apply(this, arguments);
});

Elixir(function(mix) {
    mix
        .compass('resources/assets/sass/*.scss', 'public/assets', {
            config_file: './config.rb',
            project: __dirname + '/resources/assets',
            css: '../../public/assets/css'
        });
});