Fix the leak of vSphere client sessions
Fix the leak of vSphere client sessions

Implement the test cleanup callback method to close any open vSphere
client connections. Without this clean up sessions were leaking during
testing.

openshift/kubernetes,openshift/kubernetes,csrwng/kubernetes,csrwng/kubernetes,csrwng/kubernetes,bparees/kubernetes,openshift/kubernetes,csrwng/kubernetes,bparees/kubernetes,bparees/kubernetes,csrwng/kubernetes,openshift/kubernetes,bparees/kubernetes,openshift/kubernetes,bparees/kubernetes