Add cloudstack support

[miguelaferreira]

I'm maintaining the vagrant-cloudstack plugin and got several request from colleagues to integrate it with kitchen.
I know that there is a kitchen-cloudstack plugin, but it lacks support for some of the features we use (e.g. not opening the firewall to 0.0.0.0/0, or customizing the user and private key to use with SSH). It also seems a bit of double work to implement two clients, one for vagrant and another for kitchen, when kitchen can leverage vagrant. Hence, this PR.

I did not update the README file, but I will be happy to do that if requested.

[miguelaferreira]

Some of the lines in the spec test are over the 80 chars limit. That's because the generated vagrant config has long lines due to complex config elements.
Can anyone suggest a way to break those lines without breaking the test?

[miguelaferreira]

I broke the lines that were too long, and kept the tests passing by removing the extra new line chars. I think the tests are harder to read because of that, but given the style/formatting constrains checked in the CI build that was the only way to make it pass.

[miguelaferreira]

ping @fnichol

I've rebased this PR on current master. All checks seem good.

The underlying vagrant-cloudstack plugin is being actively maintained and tested (see https://github.com/schubergphilis/vagrant-cloudstack).
I would be willing to provide a Cloudstack test environment if anyone wants to test this PR.

[bheuvel]

@fnichol / @mwrock , any chance you can have a look at this?

[smurawski]

👍 Looks good to me.

[ksubrama]

👍

[tyler-ball]

Because this is the exact same contents as openstack, can you use <% when "openstack", "cloudstack" %> instead so we don't duplicate so much?

[miguelaferreira]

@tyler-ball I've made the change you've suggested.