Reports: Proof of Play improvements

[dasgarner]

Improvements to the proof of play report:

• [ ] Add an optional filter for display group
• [ ] Page on the client not the server
• [ ] Add a total row

A note on the paging task - when there is a lot of data the report takes a long time to run and most of that time is running the query, not returning the data. Once we have the results, we don't do anything to each row - they are fully returned by the query. This means that paging is ineffective, because each page request runs the entire report again.