Merge pull request #16 from flyer103/master

改用了公用的 mongo 访问模块
Merge pull request #17 from flyer103/master

完善了 login 的逻辑
完整登入功能
Merge branch 'master' of https://github.com/YvonneZhang/jiangcai
调整 autocomplete 样式
修改width为百分比
把背景图移到 public 里面
Merge branch 'master' of https://github.com/YvonneZhang/jiangcai