Added test case for minikube config unset
Added test case for minikube config unset

dlorenc/minikube,dalehamel/minikube,warmchang/minikube,dlorenc/minikube,kubernetes/minikube,warmchang/minikube,warmchang/minikube,kubernetes/minikube,dalehamel/minikube,warmchang/minikube,dalehamel/minikube,dlorenc/minikube,kubernetes/minikube,dlorenc/minikube,dlorenc/minikube,warmchang/minikube,kubernetes/minikube,kubernetes/minikube,kubernetes/minikube,warmchang/minikube,dlorenc/minikube,kubernetes/minikube,dlorenc/minikube,dlorenc/minikube,warmchang/minikube