fix reviewer queue sorting for apps with multiple versions, remove old sort code (bug 890177)

https://github.com/ngokevin/zamboni/compare/queuesort?expand=1#diff-9a26e6efe2570209f70b06294f23ca39R469

        # (ngoke) Packaged apps with multiple versions messes up the waiting
        # time column ordering. sorted_app_ids can contain duplicate app ids,
        # one for each version pointing to the same app. If we sort based on
        # time, the app_id that shows up earlier in the list gets kept
        # after we call manual_order. When a packaged app is submitted with a
        # new version, we want it to show up at the bottom of the queue, not at
        # where its older version was. We pull out the later appearance
        # of app_id by set'ting the list in reverse. Applies only for ascending
        # sort because when descending, we want to pull the earlier appearing.

Hoping someone can understand this...but nevertheless, I has tests to show a bug was a fixed.