Delete vsphere specific code from the repository.

[roberthbailey]

What this PR does / why we need it: This PR removes the vsphere specific code from the main repository. While a new repository has not yet been created, as described in #427 (comment) I've copied all relevant files with history into https://github.com/roberthbailey/cluster-api-provider-vsphere so that a provider specific repository can be created.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #435

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

clusterctl no longer supports --provider vsphere. To create a cluster on vsphere, please use clusterctl from https://github.com/roberthbailey/cluster-api-provider-vsphere.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: roberthbailey

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [roberthbailey]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[roberthbailey]

/assign @krousey @frapposelli @dims

[k8s-ci-robot]

@roberthbailey: GitHub didn't allow me to assign the following users: frapposelli.

Note that only kubernetes-sigs members and repo collaborators can be assigned.
For more information please see the contributor guide

In response to this:

/assign @krousey @frapposelli @dims

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[krousey]

/lgtm

Did you check to see if we could clean up the vendor directory after this? I doubt it, but just want to verify.

[roberthbailey]

Yes, I ran dep ensure and nothing changed (to my surprise).