Introduce Notification Center

[UnchartedBull]

• add a new Notification center which is accessible from every screen and houses past notification (close with press), all custom actions and a clock
• Notification center can either be opened or closed by swiping from the top to open or swiping from the bottom to close
• The icon to show the notification center is shown by default, but can be hidden if your screen supports swiping nicely

Sneak Peek:

Closes #828.