Feature Request: add Docker label to all containers spawned

[CpuID]

Add something like creator=test-kitchen, or a user defined label (via .kitchen.yml) to all Docker containers spawned by test-kitchen.

Motivator: when you execute test-kitchen via CI, and you have jobs that fail, at times you end up needing to GC containers manually. This could be argued as a flaw in the CI system, but it's not always avoidable.

Various options available, but being able to filter on a label would help in mass GC'ing in these situations. eg. "find all containers with state=running && somelabel=somevalue that were created X hours ago, and docker rm -f containerid".

[CpuID]

I ended up using https://github.com/buildkite/sockguard to workaround this in the end, so less of a requirement :)