There should be an easier way to submit Java-based YARN applications

Since YARN is designed to not only work with Java, it is quite difficult and cumbersome to correctly setup a YARN application. For Java-based ones, it should be easier; there should be something like the MR2 Job API. My proposal is the following:

1. Have a basic Job / Application object, e.g. YarnApplication, which could be instantiated and configured the following:

   final Configuration conf = ...
   final YarnApplication app = YarnApplication.getInstance(conf);
   app.setContainerClassName(MyContainer.class);
   app.setJarByClass(MyContainer.class);
    

2. There should be a means to send and receive messages between container and AppMaster
3. The container should be able to report progress and state to the AppMaster
4. Bonus: A simplified WebAppMaster should start a web application and have its URL automatically proxied when run