refactor(router): rename "as" to "name" in RouteConfig

BREAKING CHANGE:

This is a rename to make routing concepts easier to understand.

Before:

```
@RouteConfig([
  { path: '/', component: MyCmp, as: 'Home' }
])
```

After:

```
@RouteConfig([
  { path: '/', component: MyCmp, name: 'Home' }
])
```

Closes #4622

Closes #4896

modules/playground/src/routing/inbox-app.ts

@@ -145,9 +145,9 @@ class DraftsCmp {
 @Component({selector: 'inbox-app', viewProviders: [DbService]})
 @View({templateUrl: "inbox-app.html", directives: [RouterOutlet, RouterLink]})
 @RouteConfig([
-  new Route({path: '/', component: InboxCmp, as: 'Inbox'}),
-  new Route({path: '/drafts', component: DraftsCmp, as: 'Drafts'}),
-  new Route({path: '/detail/:id', component: InboxDetailCmp, as: 'DetailPage'})
+  new Route({path: '/', component: InboxCmp, name: 'Inbox'}),
+  new Route({path: '/drafts', component: DraftsCmp, name: 'Drafts'}),
+  new Route({path: '/detail/:id', component: InboxDetailCmp, name: 'DetailPage'})
 ])
 export class InboxApp {
   router: Router;