Add "latest" tag on --docker-image reference in test image build
Add "latest" tag on --docker-image reference in test image build

Depending on the version of openshift and/or the registry,
the "latest" tag is needed on the binary build of the
the common test image when using an external registry.

tmckayus/oshinko-s2i,rimolive/oshinko-s2i,tmckayus/oshinko-s2i,rimolive/oshinko-s2i,rimolive/oshinko-s2i,tmckayus/oshinko-s2i