tests: add unit tests for IOProcess per SD

Change-Id: I904a33e45ad935856517b70f6bd3e6e5d56ca187
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/34578
Reviewed-by: Saggi Mizrahi <smizrahi@redhat.com>