cyclades: Series of fixes regarding networks & ips
* 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.