fsm: address acquire signal handling cleanup
ifconfig: keep lease in failed state on request failure

When requestLease fails or we loose a lease because dhcp
rebind failed, keep the lease in failed state instead to
remove it completely to allow ifstatus to consider it.
Merge pull request #391 from mtomaschewski/status-eval-2
Merge pull request #392 from mtomaschewski/status-eval-3