Arvados

When attempting to analyze Arvados v1.4 container requests, crunchstat-summary attempts to load the collection specified by the log PDH in the Container record, but that collection never exists because it is deleted immediately. Also there is no longer a `log` field for the container_request record.

For Arvados v1.4 and up, crunchstat-summary needs to be modified so that:

• for Containers, it first looks up the associated Container Request and uses the log from there
• for Container Requests, remove the current logic which looks up the associated Container log and instead load the CR log by UUID from `log_uuid` (there is no `log` field)