Refactor the UI state variables

As a part of the refactoring we separate out Samza specific state and Yarn specific state. As a result, the class SamzaAppState is moved from samza-yarn to samza-core.

The variables in the old SamzaAppState are now split into
i) Refactored SamzaAppState (in samza core)
ii)YarnAppState (in samza yarn)

Hence, we will need to change the references to SamzaAppState in all the UI scala template classes to work with the newer refactoring. This task is to create a scalatev2 directory that will include the refactored patches.