Update dockerfile to accommodate latest b2d changes.
Update dockerfile to accommodate latest b2d changes.

https://github.com/boot2docker/boot2docker/commit/2d5e77def87a9b9daa156c44bc17d8af183a4744 recently merged and it will break current b2d iso creation.
aaron-prindle/minikube,dongsupark/minikube,kubernetes/minikube,kubernetes/minikube,r2d4/minikube,mikegrass/minikube,dlorenc/minikube,kubernetes/minikube,dongsupark/minikube,dims/minikube,warmchang/minikube,dlorenc/minikube,dalehamel/minikube,dalehamel/minikube,skipjaq/minikube,kubernetes/minikube,cu12/minikube,skipjaq/minikube,dlorenc/minikube,warmchang/minikube,endocode/minikube,r2d4/minikube,warmchang/minikube,dlorenc/minikube,kubernetes/minikube,warmchang/minikube,endocode/minikube,endocode/minikube,mikegrass/minikube,warmchang/minikube,dims/minikube,warmchang/minikube,cu12/minikube,kubernetes/minikube,cu12/minikube,aaron-prindle/minikube,dalehamel/minikube,abbytiz/minikube,dlorenc/minikube,dims/minikube,mikegrass/minikube,warmchang/minikube,dlorenc/minikube,abbytiz/minikube,aaron-prindle/minikube,dongsupark/minikube,dlorenc/minikube,dlorenc/minikube,kubernetes/minikube,abbytiz/minikube,skipjaq/minikube,r2d4/minikube