Fix CreateContainerCmdImpl.withVolumesFrom()

This is the second (and last) parameter in `CreateContainerCmd` that did not work, the first being `Dns`, see #107.
Resolution was the same as in #107: move the parameter into the nested `HostConfig`.

I had some trouble understanding how the `VolumesFrom` parameter is really handled in the creation and start steps, so I added some tests that verify my assumptions.