Fix ssh keys insertion in box-repackage script
Fix ssh keys insertion in box-repackage script

Public keys are inserted correctly, but since VMs are shutdown
immediately after the filesystem modification, the data is not stored.
Call `sync` to fix that.

ntymtsiv/CloudFerry,realsystem/CloudFerry,SVilgelm/CloudFerry,roman-verchikov/CloudFerry,SVilgelm/CloudFerry,MirantisWorkloadMobility/CloudFerry,mgrygoriev/CloudFerry,roman-verchikov/CloudFerry,andybondar/CloudFerry,japaniel/CloudFerry,roman-verchikov/CloudFerry,mgrygoriev/CloudFerry,andybondar/CloudFerry,archyufa/CloudFerry,ntymtsiv/CloudFerry,realsystem/CloudFerry,MirantisWorkloadMobility/CloudFerry,ntymtsiv/CloudFerry,ntymtsiv/CloudFerry,MirantisWorkloadMobility/CloudFerry,realsystem/CloudFerry,archyufa/CloudFerry,japaniel/CloudFerry,andybondar/CloudFerry,roman-verchikov/CloudFerry,archyufa/CloudFerry,mgrygoriev/CloudFerry,japaniel/CloudFerry,SVilgelm/CloudFerry,archyufa/CloudFerry,japaniel/CloudFerry,SVilgelm/CloudFerry,MirantisWorkloadMobility/CloudFerry,andybondar/CloudFerry,mgrygoriev/CloudFerry,Settis/CloudFerry,realsystem/CloudFerry