UC-25 - Manage notifications

[cudeso]

On the notification screen, add filters. Current filter is read/unread
Additional filter: - Type - Relevant for case ID - Time
Visually improve the notification system

[cudeso]

NC/B2 List how old a notification is (days since received) and the original timestamp.
List read status
NC/C1 Visually improve the notification system
Icons. Table format.