Notifications in bell, round 2

[elisabettai]

As a result of presenting the new notification system in the UI to Team Black, these improvements were suggested:

• When there are notifications (when the bell is filled), fill it with a color. This would help because the bell might pass unnoticed to a user who's not aware of this new functionality. (I tried to don't say anything to Team Black and they did not noticed it).
• Closing notifications: once a user reads the notification (clicks on it) he might want to don't show it anymore. These possibilities were proposed:

1. Add a cross icon in the notification that will "close it" and make it disappear (forever)
2. Once the notification is read, do not show it anymore under the bell, but have still the full list elsewhere (e.g. in the user menu)
3. After the user has read the notification, store the full list for only a certain amount of time (1/2 week, maybe configurable by the user in the preferences).
4. Other ways that our UI expert might think 😉

• Extend notification to organizations: if a study/template is shared with an organization send a notification to all the members (and I'd say including the "everyone" organization, tbd)