Add osType=Windows for DC/OS deployment

[paulcallen]

Is this a request for help?:
No, other than we will want help to release it once the work is complete.

Is this an ISSUE or FEATURE REQUEST? (choose one):
Feature request that we are adding

What version of acs-engine?:
v.next

We are adding the osType=Windows for DC/OS deployment. We are doing it based on Kubernetes and Swarm and based on some prototype we have done to generate a Windows VM running a DC/OS engine.

In both cases, be ready for followup questions, and please respond in a timely
manner. If we can't reproduce a bug or think a feature already exists, we
might close your issue. If we're wrong, PLEASE feel free to reopen it and
explain why.
Orchestrator and version (e.g. Kubernetes, DC/OS, Swarm)
DC/OS

What happened:

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know:

[paulcallen]

note, @yakman2020 is working on this work in a fork of acs-engine.