qa_openstack: Fix glance image-create wait
qa_openstack: Fix glance image-create wait

glanceclient from liberty no longer outputs a status field when
calling "glance image-create". This leads to a long (60*5 s) waiting
time after creating a glance image due to our current wait loop.
Use the "--poll" option to wait until the image creation process is done
instead of the loop.

aspiers/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,aspiers/automation,SUSE-Cloud/automation,vmoravec/automation,SUSE-Cloud/automation,gosipyan/automation,aspiers/automation,vmoravec/automation,vmoravec/automation,aspiers/automation,gosipyan/automation,gosipyan/automation,vmoravec/automation,gosipyan/automation