Don't update adzerk if we don't need to.

We have been sending adzerk no op updates on every live campaign every hour (and sometimes more). These general `update_adzerk`s are not needed because any changes to the campaign/link occur in`edit_campaign`, `void_campaign`, `promotion_void`, and `charge_pending`, which have their own hooks to update adzerk.

Also rather than repeatedly deactivating an oversold campaign we will check and only deactivate it if it's active.