* Change restart policy on gvisor pod

Change the restart policy on the gvisor pod to Always. This way, if a
user runs

minikube addons enable gvisor
minikube stop
minikube start

when the addon manager tries to restart the gvisor pod, it will be
restarted and gvisor will start running automatically. This PR also adds an
integration test for this functionality.

* Test stop and start

* Revert test to delete

Revert test to delete for now, for some reason "stop" and then "start"
is failing both locally and in Jenkins for VirtualBox with a "panic test
timed out after 30 min" error

Fix .Info() error message

* upping the Makefile version
* release notes for 0.31.0

This PR adds the code for enabling gvisor in minikube. It adds the pod
that will run when the addon is enabled, and the code for the image
which will run when this happens.

When gvisor is enabled, the pod will download runsc and the
gvisor-containerd-shim. It will replace the containerd config.toml and
restart containerd.

When gvisor is disabled, the pod will be deleted by the addon manager.
This will trigger a pre-stop hook which will revert the config.toml to
it's original state and restart containerd.

Add apiserver check to "status", and block "start" until it's healthy.

* Only restart docker service if container runtime is docker

Only allow the buildroot provisioner to restart docker if the container
runtime is docker. This change should fix the bug in #3424, since now
docker will not be restarted if the container runtime is containerd.

* Added files to fix FileContent--proc-sys-net-bridge-bridge-nf-call-iptables precheck error

From this issue: https://github.com/kubernetes/kubeadm/issues/1062
these files need to be added to prevent this precheck error (which occurs when running any container runtime that isn't docker).

Also, save the machine config on the user's filesystem earlier so that the buildprovisioner can access it.

Signed-off-by: NJoeWrightss <zhoulin.xie@daocloud.io>

Add schedutils to the guest VM for the ionice command (used by k8s 1.12)

Revert "Make k8s v1.12.3 the default"

Report and clean up stale tunnel routes

kill hung test commands and improve hung process output

This reverts commit fc5256b2.

Make k8s v1.12.3 the default

none cleanup: force kubeadm, clear /etc/kubernetes, and use sudo for kubectl kill

* Add integration test to make sure minikube starts and stops with containerd
* Skip testing containerd if using none driver

Remove check for obsolete kube-dns label & validate kubernetes.default rather than localhost

Co-Authored-By: Ntstromberg <tstromberg@google.com>

Co-Authored-By: Ntstromberg <tstromberg@google.com>