Show request review progress on requests list page

[rebkwok]

Fixes #253

Show the request status and the current reviewer's progress on the request list page for each outstanding request. If their review isn't complete it says so (including if they have reviewed all files but not pressed the "Complete review" button). If their review is complete, I've assumed it's obvious from the request status and we don't need to say so.

Also made the user requests, returned and approved ones show the status in the same format as the outstanding ones.

[madwort]

haven't got time to look at the code rn, but just wanted to say I think the screenshot looks great!!