Add Windows app availability test

[sneal]

Sometimes I need the ability to test changes that involve Windows diego cells. Perhaps we can add an additional test that can be optionally invoked via:

    "optional_tests": {
      "run_windows_availbility": true
    },

I've spiked some of this out and the amount of additional code is pretty substantial just to add Windows app availability. Therefore I've been reluctant to submit a PR. Is Windows something that would even be entertained?

/cc @zmb3

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/176076639

The labels on this github issue will be updated when the story is started.

[sneal]

Here's the branch where I spiked this out https://github.com/sneal/uptimer/tree/windows

[heycait]

Hi @sneal! If you do provide a PR, we'd be happy to review it and merge it in when it's good to go. Unfortunately, given the all the other responsibilities and priorities our team is handling, we wouldn't be able to devote time to adding this ourselves.