host-deploy: ssh: flush pipes at end of command

the apache-sshd does not flush streams nor close them
this leads other side of pipe to miss last bytes

Change-Id: I0034105c473d6102283bb67d272fca2bc78f7863
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1052137
Reported-By: Piotr Kliczewski <pkliczew@redhat.com>
Tested-By: Piotr Kliczewski <pkliczew@redhat.com>
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>