fsm: Rename exclusive_owner to masterdev
fsm: Use lowerdevs.count instead of shared_users
fsm: Respect ifdown and ifup dependencies separately

Pull in masterdev in case of non-ifdown operation.
fsm: ni_ifworker_can_delete() ignores persistent
fsm: Do not fail completely on broken configuration (bnc#883203)
Merge pull request #292 pwieczorkiewicz/ifdown-fix2