Add test to get images by owner
Add test to get images by owner

A owner can have more than one image, such as
glance image-list --owner c91a45369df649278e17aaf9bf45095a
+--------------------------------------+---------------------------------+
| ID                                   | Name                            |
+--------------------------------------+---------------------------------+
| b24ca808-8918-454d-8f5f-81fd2160e27c | cirros-0.3.0-x86_64-disk        |
| 8611325e-f46c-40e7-8bcd-e86d45c0d1be | cirros-0.3.4-x86_64-uec         |
| f3cec04d-e4a2-4b43-b706-b84bebc4c71e | cirros-0.3.4-x86_64-uec-kernel  |
| 1158e4ce-baf6-4b1c-9b9d-c6717b585576 | cirros-0.3.4-x86_64-uec-ramdisk |
+--------------------------------------+---------------------------------+

So we can add this method to test get images.

Also related Link:
http://developer.openstack.org/api-ref/image/v2/#show-images

Change-Id: Ie2b0b603fe898857c77bd9002a7e7f316208143c

Juniper/tempest,sebrandon1/tempest,vedujoshi/tempest,openstack/tempest,vedujoshi/tempest,masayukig/tempest,Tesora/tesora-tempest,Tesora/tesora-tempest,cisco-openstack/tempest,masayukig/tempest,openstack/tempest,sebrandon1/tempest,cisco-openstack/tempest,Juniper/tempest