solve the bug that catagory and user can't be create
update the User.php
update composer.lock
Merge pull request #23 from Yannyezixin/hotfix/digits-count

Fixed #21, #22.

Ref: 
http://laravel.com/docs/upgrade#upgrade-4.1.26
https://github.com/laravel/framework/commit/9140b657f10d6e1a645af68573d9448bc2f94deb