Added unit test libvirtvmTests.py:TestLibvirtvm.testBuildCmdLine

Change-Id: I74b898a6398a72608d7933009644703aa3f8d831
Signed-off-by: Maciej Lichon <maciej.lichon.wroclaw@gmail.com>
Signed-off-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/14111
Reviewed-by: Vinzenz Feenstra <vfeenstr@redhat.com>