Comment 0 for bug 1053419

<capturing lisbon discussion & agreement>

At the moment we have:

/var/lib/juju/
- tools/
  - v1/
  - v2/
  - machine-0 -> ./v2
  - principal-0 -> ./v1
  - subordinate-0 -> ./v1
- agents/
  - principal-0/
    - <unit stuff>
  - subordinate-0/
    - <unit stuff>

...but this mixes stuff-in-container with stuff-outside-container. We should actually have:

/var/lib/juju/
- tools/
  - v1/
  - v2/
  - machine-0 -> ./v2
- containers/
  - principal-0/
    - var/lib/juju/
      - tools/
        - v1/
        - principal-0 -> ./v1
        - subordinate-0 -> ./v1
      - units/
        - principal-0/
          - <unit stuff>
        - subordinate-0/
          - <unit stuff>

...and ensure that the machiner, when it deploys a new container, actually *copies* its tools into the container; this chroot-without-actually-chrooting style will make it much easier to switch over to *isolated* containers when the time comes.