Add allow-root to args

Author: Ilya Radchenko

lib/bower-command.js

@@ -3,7 +3,7 @@
 var bower = process.platform === 'win32' ? 'bower.cmd' : 'bower';
 
 module.exports = function (command) {
-  var args = [command, '--config.interactive=false'];
+  var args = [command, '--config.interactive=false', '--allow-root'];
 
   return {
     command: bower,