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.
Merge remote-tracking branch 'origin/lxyxynt-devel' into yiyezhiqiu-devel

Conflicts:
	lib/schema.js
server.js 重定义修正
for merge