cyclades: Automatically adopt unknown Ganeti disks

Update 'snf-dispatcher' and 'reconciliation' mechanism to automatically
adopt unknown disks of Ganeti instances. Adoption is performed by
creating a Cyclades Volume and then renaming the instance's disk with
the volume's uuid (snf-vol-%id). The quotas for the new volume are
charged to the server's project.
cyclades: Remove volume-import management command

Remove unnecessary command, since unknown Ganeti disks are automatically
adopted by snf-dispatcher and reconciliation mechanism.