1.8.1

Release 1.8.1 is a small patch release, which updates network plugins, but also tolerates a new schemafile that will be added in kops 1.9.0. This will provide a downgrade option from kops 1.9.0.

• Ignore keyset.yaml files; provide a downgrade option from (upcoming) kops 1.9.0
• Update flannel, weave, romana, kopeio-networking, calico, canal
• Stop passing deprecated require-kubeconfig flag for kubernetes >= 1.9