Create a test environment with Docker, instead of Vagrantfile

[alexsavio]

We are using Vagrant to create a deployment testing environment.
Vagrant uses a lot of resources and probably Docker would be a better tool for this.

[bamartos]

After some investigation with Alex, moving from vagrant to "docker in docker" solution can create some issues, more info here: http://jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/.

I guess for the time being we can keep the current setup with vagrant. If someone else can have another idea feel free to post it.

Cheers,

Vasilis

[alexsavio]

In review: #11