Marking unread notification

[Boomchart]

Kindly add a button to all unread notifications as read, like mark all as read.

[mikebarlow]

Hey, this is something I've thought about but it's not in my needs right now so I likely won't get to add it just yet.
If you are needing this functionality sooner rather than later though I'll gladly accept a PR for it.

[titonova]

@Boomchart titonova/megaphone has implemented this, hopefully it's merged into this repo