re-subscribe logic

1. Re-subscribe logic in registry handler that loops subscription logic for 3 times
2. Addresses gson serialization issue by providing a simple typeadapter for handling fields of type 'class' as seen in 'Modify' -type change notification.
doesn't Observable.retry subscribe to the same stream ? I am trying to get a new stream from EurekaClient instead which would potentially connect to a different Read Server. I think I am missing something here