Handle MatchCancelled and revert all data for that match #94
Description
We need a way to cancel a match because sometimes a bug happens and wrong result is recorded.
There is already MatchCancelledEvent which we need to handle and revert all data that the MatchFinishedEvent added.
You need to make sure that MatchFinishedEvent has already happened because in some cases MatchCancelledEvent can be fired without MatchFinishedEvent.