Ansible version check

Resubmitting #964 against the dev branch.

In #454 @smashwilson and @ycombinator discussed adding fail-fast logic to the Vagrantfile to check if the Ansible version is too old to work. If you still want it, this PR does exactly that.
Yes, mine is a nitpick as well. And with the statute of limitations on nitpicks should being 24 hours (which I just made up), you should feel free to go ahead and commit this as-is if there's no more activity on this in that time period.