configurator.py: call Node's delete() for file deletion on node.

delete() unpersists and shreds the file. the previous call to unpersist
after deleting a file is wrong.

Change-Id: I7226b792c904ff8ca35054e20b85be707c080b49
Signed-off-by: Mooli Tayer <mtayer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/28821
Reviewed-by: Oved Ourfali <oourfali@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-by: Douglas Schilling Landgraf <dougsland@redhat.com>