Added missing k8s API URL env export.
Added missing k8s API URL env export.

gaia-sandbox/kubernetes-vagrant-coreos-cluster,duncanfinney/kubernetes-vagrant-coreos-cluster,BitBldr/kubernetes-vagrant-coreos-cluster,v1k0d3n/kubernetes-vagrant-coreos-cluster,ndobson/kubernetes-vagrant-coreos-cluster,RichardKnop/paas,schatt/kubernetes-vagrant-coreos-cluster,prashanthrv/kubernetes-vagrant-coreos-cluster,geseib/kubernetes-vagrant-coreos-cluster,lrolaz/kubernetes-vagrant-coreos-cluster,dqminh/kubernetes-demo,tcichowicz/kubernetes-vagrant-coreos-cluster,Hikariii/kubernetes-vagrant-coreos-cluster,pires/kubernetes-vagrant-coreos-cluster,ericjperry/kubernetes-vagrant-coreos-cluster,dqminh/kubernetes-demo,potgieterdl/kubernetes-vagrant-coreos-cluster,windwizard/kubernetes-vagrant-coreos-cluster-pub,amannm/kubernetes-vagrant-coreos-cluster,AntonioMeireles/kubernetes-vagrant-coreos-cluster,lrolaz/kubernetes-vagrant-coreos-cluster