add OpenStack etcd-manager support

[zetaab]

adds openstack support for etcd-manager, no need to use legacy anymore.

cc @drekle

/hold

lets wait that openstack support for etcd-manager is added

[zetaab]

hold until kopeio/etcd-manager#245 is merged

[zetaab]

/hold cancel

[justinsb]

I just uploaded etcd-manager 3.0.20190816 also, with the PRs for OpenStack & DigitalOcean incorporated.

[zetaab]

great!

[zetaab]

@justinsb I updated the etcd-manager in this PR as well. No need to do separate PR

[justinsb]

Thanks @zetaab

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: justinsb, zetaab

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 [justinsb]

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

[drekle]

If this is for etcd manager can we add a comment? I've been trying to do this with self documenting code and the method names, however I think its probably fine here with a comment as its just taking some of the work out of protokube.

Also not sure if there is a sane way of checking that we are using etcd manager and only opening the port in the event that the provider is not Legacy.