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
It looks like the stdlib's zip package is pretty straight forward to use for unzipping: http://golang.org/pkg/archive/zip/#example_Reader

Again, that lib shells out to the `tar` package on the system, which might be different on different systems.  I would much prefer using the docker archive package which does all of the work in native code