Initial functional checkin of the controller

Note: This does not yet handle artifacts, nor the logs from the builder-core, as we don't yet have those interfaces exposed
What do you mean by "doesn't produce streams?"  Also, a couple of points:

* using this means we're using two different packages that do almost exactly the same thing, which seems like it should be avoided if possible
* the archiver package hasn't been touch in a month and a half, which is a bit concerning
* the docker archive package has a far more robust tar implementation than this package - this package is shelling out to `tar` via `os/exec` instead of using native code