Acceptance tests

Fixes #315.
FTR The code here can start up two namespaced containers and get their IP addresses. After discussion with Tom I have started writing the tests against the tutorial VMs. They should be agnostic to Docker vs Vagrant apart perhaps from the set up and cleanup. Tests running against the Vagrant VMs will need the tester to start the VMs manually before running the suite, and perhaps all containers (within a namespace?) will be removed after each test. Tests running against Docker containers will be able to quickly start new containers for each test.