modify schema,Add interface of admin to add students,Add script to add admin.
Add dir upload to .gitignore,
modify addadmin's role to admin,
modify schema as lxyxynt,
finish funciton to upload and download resume.
修改schema.js，增加中间件判定
bug fixed
Merge remote-tracking branch 'origin/lxyxynt-devel' into yiyezhiqiu-devel

Conflicts:
	lib/schema.js
server.js 重定义修正
for merge
finish issue 49-50
Merge remote-tracking branch 'origin/master' into wangchao-devel
Merge remote-tracking branch 'origin/yiyezhiqiu-devel' into wangchao-devel
添加管理员登录