* Do not delete the network from the DB if it has associated floating
  IPs. This should never be the case because a check is made before
  deleting the network, however this check is added for safety.
* Do not allow deleting a network if there are still ports configured on
  on that network. Until now this check was for machines, but there may
  be ports that are not connected to any machine.
* Delete subnet IP pools when network is deleted.
* Get network in locked mode in network-remove cmd.
* Log error if trying to release an IPv4 address that does not belong to
  any of the IP pools of the associated subnet.
* Excluded deleted IPv4 addresses when reconciling IP pools.
* Do not set the network action to destroy when removing network from
  some backend.