Acceptance tests

Fixes #315.
I think I'd be inclined to 
 * move `Vagrantfile` into a `flocker/acceptance/tutorial_environment` directory.
 * put the `docker-tcp.socket` content into a standalone file and 
 * upload it to the nodes using the https://docs.vagrantup.com/v2/provisioning/file.html directive.
 * Update the acceptance testing documentation to say `cd acceptance/tutorial_environment && vagrant up`