Don't enable Flipper in React Native by default

Summary:
Removing default integration of Flipper from OSS till discussions happen.

To enable Flipper, just download the Flipper desktop app and uncomment the line in MainApplication.java. Flipper should automatically connect to your app.

Reviewed By: rickhanlonii

Differential Revision: D6654890

fbshipit-source-id: 692cf04fec3273703c0571d04f0100c0dbb8269b

template/android/app/src/main/java/com/helloworld/MainApplication.java

@@ -43,7 +43,6 @@ public class MainApplication extends Application implements ReactApplication {
   public void onCreate() {
     super.onCreate();
     SoLoader.init(this, /* native exopackage */ false);
-    initializeFlipper(this); // Remove this line if you don't want Flipper enabled
   }
 
   /**