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/angular1_router/src/module_template.js

@@ -31,7 +31,9 @@ function routerFactory($q, $location, $$directiveIntrospector, $browser, $rootSc
   // property in a route config
   exports.assertComponentExists = function () {};
 
-  angular.stringifyInstruction = exports.stringifyInstruction;
+  angular.stringifyInstruction = function (instruction) {
+    return instruction.toRootUrl();
+  };
 
   var RouteRegistry = exports.RouteRegistry;
   var RootRouter = exports.RootRouter;

modules/angular1_router/src/ng_route_shim.js

@@ -110,7 +110,7 @@
       routeMap[path] = routeCopy;
 
       if (route.redirectTo) {
-        routeDefinition.redirectTo = route.redirectTo;
+        routeDefinition.redirectTo = [routeMap[route.redirectTo].name];
       } else {
         if (routeCopy.controller && !routeCopy.controllerAs) {
           console.warn('Route for "' + path + '" should use "controllerAs".');
@@ -123,7 +123,7 @@
         }
 
         routeDefinition.component = directiveName;
-        routeDefinition.as = upperCase(directiveName);
+        routeDefinition.name = route.name || upperCase(directiveName);
 
         var directiveController = routeCopy.controller;