Implement option in GUI to disable checkpointing feature

When running two or more unrelated concurrent builds of the same project in Jenkins, some of the builds do not complete until the first build has completed. This is caused by the publish-over-cifs plugin and we see the following message in the console logs of the slaves that are affected: Send build artifacts to a windows share is waiting for a checkpoint on CAD Conversions #1040 . It would be great if this checkpoint feature could be turned off on a per-project basis with an option like "Don't wait for other concurrent builds to complete"