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/test/router/router_link_spec.ts

@@ -8,7 +8,7 @@ import {
   expect,
   iit,
   inject,
-  beforeEachBindings,
+  beforeEachProviders,
   it,
   xit,
   TestComponentBuilder
@@ -27,24 +27,20 @@ import {
   RouterOutlet,
   Route,
   RouteParams,
-  Instruction,
   ComponentInstruction
 } from 'angular2/router';
 
 import {DOM} from 'angular2/src/platform/dom/dom_adapter';
-import {ComponentInstruction_} from 'angular2/src/router/instruction';
-import {PathRecognizer} from 'angular2/src/router/path_recognizer';
-import {SyncRouteHandler} from 'angular2/src/router/sync_route_handler';
+import {ResolvedInstruction} from 'angular2/src/router/instruction';
 
-let dummyPathRecognizer = new PathRecognizer('', new SyncRouteHandler(null));
 let dummyInstruction =
-    new Instruction(new ComponentInstruction_('detail', [], dummyPathRecognizer), null, {});
+    new ResolvedInstruction(new ComponentInstruction('detail', [], null, null, true, 0), null, {});
 
 export function main() {
   describe('router-link directive', function() {
     var tcb: TestComponentBuilder;
 
-    beforeEachBindings(() => [
+    beforeEachProviders(() => [
       provide(Location, {useValue: makeDummyLocation()}),
       provide(Router, {useValue: makeDummyRouter()})
     ]);
@@ -106,11 +102,6 @@ export function main() {
   });
 }
 
-@Component({selector: 'my-comp'})
-class MyComp {
-  name;
-}
-
 @Component({selector: 'user-cmp'})
 @View({template: "hello {{user}}"})
 class UserCmp {