Add uplaod status UI

- Add route to get uploads by username.
- Display filename, id, timestamp and status on CSV tab
- Upload status is shown for all uploads made by currently
  logged in user. It shows *all* uploads no matter what property is
  selected.
List of files is retrieved for a username (read from the current session) so only users who can POST files can also GET those files. Other users will get an empty list.