[FEATURE ember-routing-fire-activate-deactivate-events] Fire `activate` and `deactivate` events on `Ember.Route`

Additionally to the existing `activate` and `deactivate` hooks on
`Ember.Route`, this feature adds the firing of events with the same name
on the route.

This closes #4923
Merge pull request #5569 from pangratz/add_activate_deactivate_events_to_route

[FEATURE ember-routing-fire-activate-deactivate-events] Fire `activate` and `deactivate` events on `Ember.Route`