fs: Set target host and work dir for fs haul driver

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
ovz: Create root dir if it doesn't exist

This can happen when rsyncing the FS over two nodes.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
fs: Initial implementation of subtree fs hauler

We have (legacy?) scenario when container gets migrated with
its FS, the latter is copied from source node to destination
with the rsync.

This is the implementation of stupid double rsync -- one time
before dumping, the other one -- after freezing. Some more
sophisticated rsyncing/iterations interaction might be required.

And one problem -- while cpoying files, inodes do change and
restoring fsnotify via handles doesn't work.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>