The go program we use to get binaries from a docker image was unpacking
only the last layer. This is not required and in order to have a more
generic approach and fewest requirement the program now unpack all the
image
Tinkerbell is made of different components as we all know at this point.
Sandbox had those versions all over the places. This PR moves them as
part of the `envrc` file.
As it is today this PR requires an additional flag for the `docker-compose` command as described here #6
