refactor(core): change module semantics

This contains major changes to the compiler, bootstrap of the platforms
and test environment initialization.

Main part of #10043
Closes #10164

BREAKING CHANGE:
- Semantics and name of `@AppModule` (now `@NgModule`) changed quite a bit.
  This is actually not breaking as `@AppModules` were not part of rc.4.
  We will have detailed docs on `@NgModule` separately.
- `coreLoadAndBootstrap` and `coreBootstrap` can't be used any more (without migration support).
  Use `bootstrapModule` / `bootstrapModuleFactory` instead.
- All Components listed in routes have to be part of the `declarations` of an NgModule.
  Either directly on the bootstrap module / lazy loaded module, or in an NgModule imported by them.

modules/@angular/compiler/testing/directive_resolver_mock.ts

@@ -27,8 +27,11 @@ export class MockDirectiveResolver extends DirectiveResolver {
 
   private get _compiler(): Compiler { return this._injector.get(Compiler); }
 
-  resolve(type: Type): DirectiveMetadata {
-    var dm = super.resolve(type);
+  resolve(type: Type, throwIfNotFound = true): DirectiveMetadata {
+    var dm = super.resolve(type, throwIfNotFound);
+    if (!dm) {
+      return null;
+    }
 
     var providerOverrides = this._providerOverrides.get(type);
     var viewProviderOverrides = this.viewProviderOverrides.get(type);