added new Java API to list views

I added a few methods on Service to list views for specific apps and search criteria. Please review the code.
To make the API more handy, we can also add getViews() method on Application object.

I also attached sample code to list visible dashboards for one app. But please ignore commit e59380b since it's not a real test case. You can add more formal unit test and sample code in the official repo.