- Add registry to register all supported drivers in different platforms.
- Add DriverDef to define driver's metadata.
- All driver support logic moved to pkg/minikube/drivers, removed all
  driver name switches scattered in different packages.

Use ListDrivers() method to get the list of VM drivers.
SupportedVMDrivers become the whole list of VM drivers on all
platforms, which is used in gendocs only.

Different platform has differnet list of supported drivers. The
registry contains the correct list of drivers that are supported. In
future we could add commands like `minikube list-drivers`

Type fix "iso"->"ISO"

In this doc, "ISO" is written some in capitals, some not in. please keep consistency.

Documentation fix.

Resolves #2559

Remove --skip-preflight-checks, ignore unwanted checks

Update to k8s v1.9.3.

Before we would hardcode the repo path that we are looking for.
Currently we include everything from the organization (k8s.io).

Before we would only add the files from the dependencies,
not the file from the actual module (such as "main.go").

Instead of running `go list` every time (very slow),
cache the results in the build folder and include it.

Add a shell helper script, to make the Makefile more
readable. Use regular "makedepend" syntax for output.

Make sure that all invocations are identical, before trying to make
a function out of it. Also clean up whitespace and similar changes.

Having a phony target as a minikube dependency means that
it always needs to be rebuilt/copied, which is unnecessary.

Also clean up and simplify the syntax, thereby avoiding the
current copy/paste errors (that always come with duplication)

Adds note for specifying docker bridge for vm-driver=none

Fixes #2571

Add metrics-server as an addon

With passthrough mode we can enable KVM nesting for guests.

Fixes #2553
Signed-off-by: NFabian Deutsch <fabiand@fedoraproject.org>

This reverts commit 7a4babe1d6d0e90da3b8101cb349735f0ac16b1e.

For now we just hard-code passthrough.
Signed-off-by: NFabian Deutsch <fabiand@fedoraproject.org>

This patch enables KVM support inside the ISO to support nesting.
Signed-off-by: NFabian Deutsch <fabiand@fedoraproject.org>

Before this patch the virtual CPU was the stock qemu CPU, in the sense that
the virtual CPU features were set according to the default qemu CPU.

With this change the CPU features of the host will be copied at start to the
domain definition. This includes features like svm and vmx, which in turn allow
to run nested virtualization if the host is configured accordingly i.e.
`kvm_intel nested=y` in `/etc/modprobe.d/kvm.conf`.

To turn on nesting, a user has to specify `--kvm-cpu-model host-model` when
creating the VM.

Resolves #2553
Signed-off-by: NFabian Deutsch <fabiand@fedoraproject.org>

Switch default bootstrapper to kubeadm

This is a mismatch issue between new minikube versions and old ISO versions. It's
also unlikely to cause a real issue because it requires users to opt-into crio and
modify crio-specific settings to cause trouble.

highlight shell samples quoted in docs

Propose fix a typo

Refactor get download url for minikube