All previous versions of doAzureParallel unable to orchestrate jobs #341

The merge of PR336 (#336) is the root cause of the bug I attempted to fix in #340. However, the bug fix did not succeed.

By merging PR336 to master, the file at https://raw.githubusercontent.com/Azure/doAzureParallel/master/inst/startup/cluster_setup.sh was changed. The file is referenced in old versions of doAzureParallel (see e.g. https://github.com/Azure/doAzureParallel/blob/v0.6.3/R/cluster.R#L145). Since the set up of docker was removed by this PR, all pools/jobs orchestrated using previous versions of doAzureParallel will fail until this PR is reverted or docker is installed again by the cluster_setup.sh file. It is unclear to me if the version on master currently works.

This change has broken the daily runs in our production system relying on Batch for two days now. What can I do to help fix this?