Desktop Notification

## Overview

Desktop Notification

Show notification window when events occured.
Events: Someone sent message, Someone responded to messsage, and so on

![desktop-notification](https://f.cloud.github.com/assets/2914192/1692649/9cbdc72e-5e80-11e3-97fc-25840e5eb450.png)

## Known problems

1. Notification window only notify you
If you clicked notification window,  nothing will occur.
I want to show Browser when window was clicked,  but I do not know how to do
2. Confirmation dialog will appear on each **RELOAD**.  *Chrome Only*
Chrome deos not have property `Notification.permission`, so script judge **Do not have permission** at first time.
3. Notification window will closed automatically 4 or 5 seconds after shown.  *Firefox Only*
This is caused by Firefox's [bug](http://stackoverflow.com/questions/19144097/prevent-firefox-web-notifications-from-automatically-closing)

## Please check

Released this change to staging environment.  Please check various operations.

https://atmos.interprism.co.jp/atmos-web-stg/
user1: bob/BOB
user2: john/JOHN