(Problem) Invalid contract not complying with AuRa rules

(Solution) Implement a method `finalizeChange` that will only be allowed to be called from SYSTEM, according to the parity spec, in order to let it run in parity 1.8.3
Current situation:
```
2017-11-25 18:45:54  Encountered error on making system call: Bad instruction fd
```
It can't make a system call because the contract is not valid