notify user when tokens have expired

[cdrani]

Notify users that tokens have expired and that once they visit the site they will need to click on the browser action. An ideal notification would just be adding a badge on the extension icon. As the tokens expire every 5 days from the day of generation, there are potentially two solutions:

1. Just get the date that the browser actions was clicked and then exactly five days later (I think that's how long before the tokens expire) add the badge to notify the user.

2. When a token is generated and user is redirected to kdrama site, the token expiration date and time is shown at the footer of the page. You can access this info to notify the user at a more precise time that their token is about to expire and/or expired.

Ideally the second option is better, but either would work just as well.