cyclades: Handle errors during vm creation
Commit #f2080d1 mocked an OP_INSTANCE_REMOVE when enqueuing an OP_INSTANCE_CREATE job to Ganeti failed. However, this may result in releasing IPs that may get reserved in Ganeti, because we can never really know if the job has reached Ganeti or not (e.g. timeout). For this reason, we should *never* delete the VM. Instead we mark the VM as being in error state. The user must explicitly delete the server. This has the downside, that we return 202 with the resulting VM being in ERROR state. However, this is the only way to be really secure.