docs: function(done) {
                  var source = __dirname + '/background.js';
                  var dest = self.dir + '/background.js';
  
                  fs.readFile(source, 'utf8', function(err, background) {
                      if (err) return done(err);
  
                      // Make background.js connect with the websocket server on
                      // this port
                      background = background.replace('$PORT', self.port);
                      fs.writeFile(dest, background, done);
                  });
              }