:run_at not respected, and not documented.

[CullenShane]

When creating jobs and passing in :run_at, all seems to be well, except for nothing happens. The job is run immediately as soon as the worker sees it.

It appears that a replacement :delay has been added, but this also seems to do nothing.

Worst, there is no documentation that :runs_at does not work as documented in delayed_job.

:runs_at usually works by a special select statement which only grabs records which are set to be run in the past from the current time. When using a queue-based data source, this type of selection is not possible, so some other method of delaying a job must be put into place.