refactor(WebWorker): Use the new generic bootstrap.

BREAKING CHANGE:

You can no longer bootstrap a WebWorker or Isolate using `bootstrap` or `bootstrapWebWorker`. Instead you have to do the following:

In TypeScript:
```TypeScript
// index.js
import {WORKER_RENDER_PLATFORM, WORKER_RENDER_APPLICATION, WORKER_SCRIPT} from "angular2/platforms/worker_render";
import {platform} from "angular2/platform";

platform([WORKER_RENDER_PLATFORM])
.application([WORKER_RENDER_APPLICATION, new Provider(WORKER_SCRIPT, {useValue: "loader.js"});
```
```JavaScript
// loader.js
importScripts("https://cdnjs.cloudflare.com/ajax/libs/es6-shim/0.33.3/es6-shim.js", "https://jspm.io/system@0.16.js", "angular2/web_worker/worker.js");
System.import("app");
```
```TypeScript
// app.ts
import {Component, View} from "angular2/core";
import {WORKER_APP_PLATFORM, setupWebWorker} from "angular2/platforms/worker_app";
import {platform} from "angular2/platform";

@Component({
  selector: "hello-world"
})
@View({
  template: "<h1>Hello {{name}}</h1>
})
export class HelloWorld {
  name: string = "Jane";
}

platform([WORKER_APP_PLATFORM])
.asyncApplication(setupWebWorker, optionalProviders?)
.then((ref) => ref.bootstrap(RootComponent));
```

In Dart:
```Dart
// index.dart
import "angular2/platform.dart";
import "angular2/platforms/worker_render.dart";

main() {
  platform([WORKER_RENDER_PLATFORM])
  .asyncApplication(initIsolate("my_worker.dart"));
}
```
```Dart
// background_index.dart
import "angular2/platform.dart";
import "angular2/platforms/worker_app.dart";
import "package:angular2/src/core/reflection/reflection.dart";
import "package:angular2/src/core/reflection/reflection_capabilities.dart";

@Component(
  selector: "hello-world"
)
@View(
  template: "<h1>Hello {{name}}</h1>"
)
class HelloWorld {
  String name = "Jane";
}

main(List<String> args, SendPort replyTo) {
  reflector.reflectionCapabilities = new ReflectionCapabilities();
  platform([WORKER_APP_PLATFORM])
    .asyncApplication(setupIsolate(replyTo))
      .then((ref) => ref.bootstrap(RootComponent));
}

```

You should no longer import from the `angular2/web_worker/worker` and `angular2/web_worker/ui` paths. Instead you can now import directly from core, directives, etc..

The WebWorkerApplication class has been removed. If you want to use ServiceMessageBroker or ClientMessageBroker on the render thread, you must inject their factories via DI.
If you need to use the MessageBus on the render thread you must also obtain it through DI.

closes #3277
closes #5473

Closes #5519

modules/angular2/src/web_workers/debug_tools/multi_client_server_message_bus.dart

@@ -57,16 +57,17 @@ class MultiClientServerMessageBus extends GenericMessageBus {
 }
 
 class WebSocketWrapper {
-  WebSocket socket;
+  WebSocket _socket;
   Stream stream;
   int _numResultsReceived = 0;
   bool _isPrimary = false;
   bool caughtUp = false;
   List<String> _messageHistory;
   List<int> _resultMarkers;
+  StreamController<String> _sendStream;
 
-  WebSocketWrapper(this._messageHistory, this._resultMarkers, this.socket) {
-    stream = socket.asBroadcastStream();
+  WebSocketWrapper(this._messageHistory, this._resultMarkers, this._socket) {
+    stream = _socket.asBroadcastStream();
     stream.listen((encodedMessage) {
       var messages = JSON.decode(encodedMessage);
       messages.forEach((data) {
@@ -78,6 +79,13 @@ class WebSocketWrapper {
         }
       });
     });
+
+    _sendStream = new StreamController<String>();
+    _socket.addStream(_sendStream.stream);
+  }
+
+  void send (String data) {
+    _sendStream.add(data);
   }
 
   bool get isPrimary => _isPrimary;
@@ -113,7 +121,7 @@ class WebSocketWrapper {
       numMessages = end - curr;
     }
     while (numMessages > 0) {
-      socket.add(_messageHistory[curr]);
+      send(_messageHistory[curr]);
       curr++;
       numMessages--;
     }
@@ -144,7 +152,7 @@ class MultiClientServerMessageBusSink extends GenericMessageBusSink {
     String encodedMessages = JSON.encode(messages);
     openConnections.forEach((WebSocketWrapper webSocket) {
       if (webSocket.caughtUp) {
-        webSocket.socket.add(encodedMessages);
+        webSocket.send(encodedMessages);
       }
     });
     messageHistory.add(encodedMessages);