a bit cumbersome right now

- jenkinsfile sets us up
- contain passes known vars into container
- run patches them into the vars.json
- main.pm loads tests dependent on the vars (I think)

could probably get away with master and selective --device forward, but
we can't use a slave as userns is screwing image permissions up so the
image is effectively not able to do anything if we were to switch it into
priv mode.

at the same time --device mapping apparenlty wouldn't give access either
unless one messes with the dev acls (maybe)

https://github.com/docker/docker/issues/28986

otherwise tests will just not ever finish as the IO is so bloody slow