[FEATURE ember-routing-transitioning-classes] namespace classes

Use .ember-transitioning-in and .ember-transitioning-out
instead of non-ember-namespaced classes.
[FEATURE ember-routing-transitioning-classes] enable this feature
Merge pull request #9987 from machty/ember-transitioning-in

[FEATURE ember-routing-transitioning-classes] namespace classes
Stream-based shouldDisplay checking

Closes #9895.
Merge pull request #9988 from ef4/fix-inline-if

Stream-based shouldDisplay checking
Make Router.map callbacks invoke after application boot.
[FEATURE ember-routing-named-substates]

Only add loading and error substates if the resolver being used is a
modules based resolver.

Also, return the Ember.Router from `Ember.Router.map` instead of the
`router.js` router.