refactor(router): improve recognition and generation pipeline

This is a big change. @matsko also deserves much of the credit for the implementation.

Previously, `ComponentInstruction`s held all the state for async components.
Now, we introduce several subclasses for `Instruction` to describe each type of navigation.

BREAKING CHANGE:

Redirects now use the Link DSL syntax. Before:

```
@RouteConfig([
  { path: '/foo', redirectTo: '/bar' },
  { path: '/bar', component: BarCmp }
])
```

After:

```
@RouteConfig([
  { path: '/foo', redirectTo: ['Bar'] },
  { path: '/bar', component: BarCmp, name: 'Bar' }
])
```

BREAKING CHANGE:

This also introduces `useAsDefault` in the RouteConfig, which makes cases like lazy-loading
and encapsulating large routes with sub-routes easier.

Previously, you could use `redirectTo` like this to expand a URL like `/tab` to `/tab/posts`:

@RouteConfig([
  { path: '/tab', redirectTo: '/tab/users' }
  { path: '/tab', component: TabsCmp, name: 'Tab' }
])
AppCmp { ... }

Now the recommended way to handle this is case is to use `useAsDefault` like so:

```
@RouteConfig([
  { path: '/tab', component: TabsCmp, name: 'Tab' }
])
AppCmp { ... }

@RouteConfig([
  { path: '/posts', component: PostsCmp, useAsDefault: true, name: 'Posts' },
  { path: '/users', component: UsersCmp, name: 'Users' }
])
TabsCmp { ... }
```

In the above example, you can write just `['/Tab']` and the route `Users` is automatically selected as a child route.

Closes #4170
Closes #4490
Closes #4694
Closes #5200

Closes #5352

modules/angular2/src/router/async_route_handler.ts

@@ -1,13 +1,19 @@
-import {RouteHandler} from './route_handler';
 import {Promise, PromiseWrapper} from 'angular2/src/facade/async';
 import {isPresent, Type} from 'angular2/src/facade/lang';
 
+import {RouteHandler} from './route_handler';
+import {RouteData, BLANK_ROUTE_DATA} from './instruction';
+
+
 export class AsyncRouteHandler implements RouteHandler {
   /** @internal */
   _resolvedComponent: Promise<any> = null;
   componentType: Type;
+  public data: RouteData;
 
-  constructor(private _loader: Function, public data?: {[key: string]: any}) {}
+  constructor(private _loader: Function, data: {[key: string]: any} = null) {
+    this.data = isPresent(data) ? new RouteData(data) : BLANK_ROUTE_DATA;
+  }
 
   resolveComponentType(): Promise<any> {
     if (isPresent(this._resolvedComponent)) {