Add support for quiet period

[pendragon]

Jenkins allows scheduling jobs with a delay period. To support this one has to add a `delay` parameter which takes integer values giving the seconds to wait until starting the job.

Basically `build_job_url(...)` as to be extended to include that parameter. While it already works for POST requests by adding that parameter, GET requests currently offer no way to add that. I can provide a patch if you're interested.

[Roger Firpo Curcoll (roger-firpo)]

I would be very interested in seeing this bug resolved.