add clean up before running windows test

exit out of the soft start test if we can't find old config

Upgrade oldest k8s version supported to 1.13

bump default kubernetes version to 1.18.3

skip two always failing test on windows and create issue

Add Ambassador Ingress controller as an addon

Make sure multinode clusters can survive restarts

respect native-ssh param properly

integration tests: fix docker-env test in powershell