We still have a variety of build artifacts that can't be cleaned up, because of permissions problems.

When IAM is launched, we should use it to correct as many problems as possible.

We should be able to detect the problematic files in gs://chromes-image-archive/ and gs://chromeos-releases by looking at the log files from purge runs.

We will also want to cleanup a variety of very old board specific buckets in chromeos.int.bot, when it's feasible.