Update to docs to Docker 1.0.0

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Use busybox in fixtures, instead of ubuntu

Signed-off-by: d11wtq <chris@w3style.co.uk>
Merge pull request #249 from d11wtq/performance/busybox_fixtures

Use busybox in fixtures, instead of ubuntu
Merge pull request #248 from orchardup/docker-1.0.0

Update to docs to Docker 1.0.0