refactor(core): introduce ComponentFactory.

Each compile template now exposes a `<CompName>NgFactory` variable
with an instance of a `ComponentFactory`.
Calling `ComponentFactory.create` returns a `ComponentRef` that can
be used directly.

BREAKING CHANGE:
- `Compiler` is renamed to `ComponentResolver`,
  `Compiler.compileInHost` has been renamed to `ComponentResolver.resolveComponent`.
- `ComponentRef.dispose` is renamed to `ComponentRef.destroy`
- `ViewContainerRef.createHostView` is renamed to `ViewContainerRef.createComponent`
- `ComponentFixture_` has been removed, the class `ComponentFixture`
  can now be created directly as it is no more using private APIs.

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

@@ -69,10 +69,10 @@ export function main() {
                      provide(Console, {useClass: DummyConsole})
                    ])
              .then((applicationRef) => {
-               var router = applicationRef.hostComponent.router;
+               var router = applicationRef.instance.router;
                router.subscribe((_) => {
                  expect(el).toHaveText('outer { hello }');
-                 expect(applicationRef.hostComponent.location.path()).toEqual('');
+                 expect(applicationRef.instance.location.path()).toEqual('');
                  async.done();
                });
              });