安装 new.laravel-china.org 时报错，缩印字段长度超，怎么解决?

安装news.laravel-china.org的时候，运行后 artisan est:instal 后，出现如下错误，尝试换了几个数据库的编码，都不能解决。只能去数据库迁移文件里，限制一下字段的长度才行。是我错过了哪一步或者数据库配置不正确吗？

  [Illuminate\Database\QueryException]                                                                                                                                             
  SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes (SQL: alter table `tags` add unique `tags_slug_unique`(`slug`))  

  [PDOException]                                                                                                   
  SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes