Need a way to have jobs disabled on creation

[dhumeniuk]

We have several jobs (10 or so) that run on the master. We don't have enough executors to support running all of those jobs for every single branch. Also, not all jobs are that important for certain changes. We have jobs that run GUI integration tests that don't really need to be run for non GUI changes. It would be nice to have a flag for whether all jobs are disabled (even if the master job is enabled).