Add support for create/start/stop/delete of containers

As it says on the tin (I hope). Since image support doesn't yet exist, we simply hardcode the image to trusty.
Not familiar with Go but what happens if subuid/subgid are invalid and contain less than 3 columns?

My guess is that accessing s[1] or s[2] in that case would throw an exception or fail in some way which doesn't appear to be handled there.