* tasks dependencies
* FindAddresses should proceed even if LBID is empty
* refacto instance: handle several instances in IG + volumeSize in model
* refacto lb_backend: set servers' IPs in backend task rather than instance
* dns changes for tf support
* render Scaleway s3 objects + add zone to outputs
* add terraform support to documentation
* new instance unique name should be given according to actual instances names
* avoid untimely changes in tf + tag instance IPs to avoid orphaned IPs at cluster deletion
* update integration tests
* review comments
* add IPs to the resources to be deleted with the cluster
* add task + model for DNS record