Upgraded to v1beta2

Few comments on the migration:

* The flags field wasn't added back to the ReadsRDD. 
* As part of the migration utils-java was also upgraded, and the RetryPolicy removed.
* Also sneaked in a change to make applicationName='spark-examples' instead of the class name, so not every example needs to be authorized.

Fix #50 
I think it makes sense, @cassiedoll also has some thoughts on this. https://github.com/googlegenomics/spark-examples/issues/50#issuecomment-62175512