Add Vagrant VM support for user unit-testing

[nima]

As brought to light in #22, unit-testing has become a dangerous thing - that shouldn't be the case as it kind of defeats the purpose of having unit-testing.

Instead of leaving it upto the user to set up their own VM environment for unit-testing, it would be nice to offer some automation.

How is not clear, but it appears that Vagrant VM is a good way forward.

[nima]

Perhaps a clean solution would be to parse the existing .travis.yml file and do what TravisCI does; this way we only configure unit-testing in one place.