With the permission of Romain Degez, CTO of Smartjog.

Signed-off-by: Sébastien Luttringer <sebastien.luttringer@smartjog.com>

Replaced all logger call in child.
Added dedicated libev loop.
Handle exceptions using fatal helpers of ForkedJob.

Replace logging calls with sys.stderr.write in order to prevent deadlock in the
fork.

Needed for disk synchronisation during live migration.

Harmless renaming.

These jobs are needed for VM migration/clone.