delete global variable: "g_Data"
1. create libs directory and move jstree to it
2. extract some google drive code to /libs/google-drive.js
in google-drive.js: hide handleAuthResult function instead use onAuthFail and onAuthSuccess.
add libs directory(previous forget to added to git)
comment some code
commend some code
Merge branch 'pr/4'

Conflicts:
	web/index.html