* Reject previous unaccepted serials if action is 'DESTROY'. This is
  required because multiple DESTROY actions may be pending for the same
  resource (e.g. VM). The one who succeeds will be accepted, while all
  others will be rejected. This isn't optimal since it causes circular
  issuing and rejection of commissions and should be fixed in a better
  way.
* Update dispatcher to handle commissions before updating the state of
  the VM, since if a new commission will be issued, this commission will
  depend on the state of the VM.