Notifications in Navbar

Closes #151 

Works on the `notifier` service, that has been around for a while, but dormant.

We had a `NotifierCtrl` before - this is gone now. Messages are displayed by directives only.
The navbar is still the place to hold them. A configuration section has been added to configure the notifier - the max number of messages kept can be configured, as well as a duration that determines how long notifications stay up on the screen. Both come with sensible default values - it's not a necessity to include a notifier section in the configuration file.

A message menu displays archived messages - they are accessed through a button in the navbar. Their current location isn't really nice (in a panel below the navbar), they need at least a transition probably.

Speaking of transitions - they would generally be nice to add here, but we are either using Foundation's top bar wrong or it just behaves weird. Might be better to role our own navbar at some point, shouldn't be too hard to do.

All of it obviously needs more work and be done a whole lot nicer.

Specs for the notifier service are included.