Notification overlay Messages and Alerts sections

Shift to new API to support 2 tab view
When a new has no messages they will see the old style overlay with
Notifications heading. I have added tests to assure this is the case!

Later patches will:
1) Add the mark as read button only in message view
2) Note currently the tabs do not refresh when notifications is clear.
We need some kind of EventEmitter to make this sort of thing easier.

Change-Id: I62b590e81cd3fe867c4c13959cb43466aacfe2d5