Updates NotificationService to support custom views

This allows us to inject small UI components as overlays ontop of
editors
Confirm navigating away from unsaved content
Fixes missing dependencies
Merge branch '7.1.0-LocationChangeNotificatiion' into 7.1.0
Merge branch '7.1.0' of https://github.com/umbraco/Umbraco-CMS into 7.1.0