Use an outlet for the sub routes of the admin area

With the use of an outlet, the routing is now more consistent with how routing is implemented for the rest of the application. It is no longer necessary to pass the route as data and use custom routing logic for sub routes. Components are no longer hard wired inside the AdminHomeComponent. As a noticible effect, the summary bar is no longer reloaded when switching sub routes.

Closes: #782 (closed)
Depends-on: !1154 (merged)