Reviewed Reportbacks view

Closes #3611 - Adds a Reviewed tab to the Reportbacks forms, displaying all reviewed reportbacks, and allowing filtering by Review Status.

The Reportback File entity is displayed as a rendered entity.  This is done via adding a `ReportbackFileEntityController` entity `buildContent` method, and changes to  `dosomething_reportback_entity_info`:

-  exposing the Reportback File entity as viewable with a `full` view mode in 
- Also exposes the Reportback File entity properties to views

Removes the existing `node_reportbacks` and `user_reportbacks` views, and removes the `dosomething_reportback_views_data` hook which those views used.

![reviewed](https://cloud.githubusercontent.com/assets/1236811/5463525/c7bf8550-854b-11e4-9a9d-1db6f231dc4f.png)