Make minikube (and kvm2) installable with "yum"

[afbjorklund]

When we do the apt indexing of the .deb packages*,
we might as well do the yum indexing of the .rpm.

• See Make minikube (and kvm2) installable with "apt" #3110

This should include both minikube and the kvm2 driver...
That is, the new docker-machine-driver-kvm2 package*.

• See Debian package should include the kvm driver (docker-machine-driver-kvm2) #2982

---

Basically, provide something similar to what kubectl has:

https://kubernetes.io/docs/tasks/tools/install-kubectl/#install-using-native-package-management

• https://packages.cloud.google.com/apt/ (xenial)

• https://packages.cloud.google.com/yum/ (el7)

This includes signing the packages with a GPG key.

Not sure if we can use the Google Cloud Packages ?

• https://packages.cloud.google.com/apt/doc/apt-key.gpg

• https://packages.cloud.google.com/yum/doc/yum-key.gpg

[tstromberg]

Upstream request: kubernetes/release#839

[afbjorklund]

Current packages available at:

• https://storage.googleapis.com/minikube/releases/v1.3.0/minikube-1.3.0.rpm
• https://storage.googleapis.com/minikube/releases/v1.3.0/docker-machine-driver-kvm2-1.3.0.rpm