Add a browser tab notification on new feed items available

[blatinier]

It could be great to have auto feed refresh (let's say every 5min) and a browser tab notification (see the link at the end of the issue for implementation example).

http://webdesign.tutsplus.com/tutorials/how-to-display-update-notifications-in-the-browser-tab--cms-23458

[jaesivsm]

Set for the next feature batch. It's a whole new mechanic to set up.