Description of problem:

Every job should have a priority so that if there are enqueued jobs the new jobs with higher priority are executed first.

For instance:

1- There are 100 reposync jobs currently running. There are another 50 jobs waiting to run because the capsules cannot run all of them concurrently.

2- Some errata is published and the customer wants to immediately apply it. The customer should be able to apply a higher priority to the "apply errata" jobs. Therefore, the reposync jobs that are queued will only run after the errata jobs have finished.