Delay between retries

Maybe this is a duplicate. In that case, of course just close.

It should be possible to set a time to wait for a job to retry. In some cases it doesn't make sense to immediate retry a job. For example 

- I have a job, to imports data from a remote resource. If the resource isn't reachable, it isn't probably reachable 1 second later.
- I have a job, that stresses the server quite much. In that case, when the job fails, I want to let the server cool down and other jobs can run without interruption, before I stress the server once more.