Job DSL support

[buep]

Scripting job using pipelines are part of other existing issues, but for job dsl script support there needs to be written more code and it is more work.

It should be done as this is the other way users script their jobs, to avoid configure Jenkins by hand.

[geoffwhittington]

I understand the value of this capability and I understand that it can facilitate on-boarding the plugin more effectively. We have to decide on the timing for it, here.