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 #4728
Closes #4228
Closes #4170
Closes #4490
Closes #4694
Closes #5200

Closes #5475

modules/angular2/test/router/integration/router_link_spec.ts

@@ -9,7 +9,7 @@ import {
   expect,
   iit,
   inject,
-  beforeEachBindings,
+  beforeEachProviders,
   it,
   xit,
   TestComponentBuilder,
@@ -21,7 +21,7 @@ import {NumberWrapper} from 'angular2/src/facade/lang';
 import {PromiseWrapper} from 'angular2/src/facade/async';
 import {ListWrapper} from 'angular2/src/facade/collection';
 
-import {provide, Component, DirectiveResolver} from 'angular2/core';
+import {provide, Component, View, DirectiveResolver} from 'angular2/core';
 
 import {SpyLocation} from 'angular2/src/mock/location_mock';
 import {
@@ -35,7 +35,8 @@ import {
   Route,
   RouteParams,
   RouteConfig,
-  ROUTER_DIRECTIVES
+  ROUTER_DIRECTIVES,
+  ROUTER_PRIMARY_COMPONENT
 } from 'angular2/router';
 import {RootRouter} from 'angular2/src/router/router';
 
@@ -47,16 +48,12 @@ export function main() {
     var fixture: ComponentFixture;
     var router, location;
 
-    beforeEachBindings(() => [
+    beforeEachProviders(() => [
       RouteRegistry,
       DirectiveResolver,
       provide(Location, {useClass: SpyLocation}),
-      provide(Router,
-              {
-                useFactory:
-                    (registry, location) => { return new RootRouter(registry, location, MyComp); },
-                deps: [RouteRegistry, Location]
-              })
+      provide(ROUTER_PRIMARY_COMPONENT, {useValue: MyComp}),
+      provide(Router, {useClass: RootRouter})
     ]);
 
     beforeEach(inject([TestComponentBuilder, Router, Location], (tcBuilder, rtr, loc) => {
@@ -240,8 +237,8 @@ export function main() {
              .then((_) => router.config([new Route({path: '/...', component: AuxLinkCmp})]))
              .then((_) => router.navigateByUrl('/'))
              .then((_) => {
-               rootTC.detectChanges();
-               expect(DOM.getAttribute(rootTC.debugElement.componentViewChildren[1]
+               fixture.detectChanges();
+               expect(DOM.getAttribute(fixture.debugElement.componentViewChildren[1]
                                            .componentViewChildren[0]
                                            .nativeElement,
                                        'href'))
@@ -386,10 +383,7 @@ class MyComp {
   name;
 }
 
-@Component({
-  selector: 'user-cmp',
-  template: "hello {{user}}"
-})
+@Component({selector: 'user-cmp', template: "hello {{user}}"})
 class UserCmp {
   user: string;
   constructor(params: RouteParams) { this.user = params.get('name'); }
@@ -425,17 +419,11 @@ class NoPrefixSiblingPageCmp {
   }
 }
 
-@Component({
-  selector: 'hello-cmp',
-  template: 'hello'
-})
+@Component({selector: 'hello-cmp', template: 'hello'})
 class HelloCmp {
 }
 
-@Component({
-  selector: 'hello2-cmp',
-  template: 'hello2'
-})
+@Component({selector: 'hello2-cmp', template: 'hello2'})
 class Hello2Cmp {
 }
 
@@ -455,7 +443,6 @@ function parentCmpLoader() {
   new Route({path: '/better-grandchild', component: Hello2Cmp, name: 'BetterGrandchild'})
 ])
 class ParentCmp {
-  constructor(public router: Router) {}
 }
 
 @Component({