Allow closing/finalizing the campaign after any round

[atsirlin]

-- Back-end task --

Presently, Montage would only allow to close/finalize the campaign after the ranking round. However, our current experience is that not more than 50% of the campaigns proceed to the ranking round, while others end at the yes/no or rating rounds. These campaigns can't be closed, but they have to be closed, at least for the purpose of cleaning the dashboard. Therefore, we need the option of closing the campaign after its last round has been finalized, no matter what kind of round it was.