refactor(render): use render layer fully

Introduces angular2/src/core/compiler/ViewFactory which
extracts ProtoView.instantiate and replaces ViewPool.

Note: This is a work in progress commit to unblock other commits.
There will be follow ups to add unit tests, remove TODOs, …

test-init.dart

@@ -0,0 +1,5 @@
+import 'package:angular2/src/dom/browser_adapter.dart';
+
+main() {
+  BrowserDomAdapter.makeCurrent();
+}